 In the previous lecture, we have learnt about cast irons and cast heels. Now, in this lecture, let us learn about aluminium and magnesium castorloys. First we will see the aluminium castorloys, next we will see the magnesium castorloys, aluminium castorloys. First, let us see the characteristics of aluminium. Aluminium is light in weight, its specific weight is substantially lower than other common metals. Aluminium alloys are suitable for all known casting process, means there are different casting process are there, sand casting, die casting, investment casting, aluminium can be used for all the casting process. Aluminium has outstanding formability and can be processed in variety of ways. Next, aluminium alloys are distinguished by an excellent degree of homogeneity, means the uniform composition everywhere. Aluminium and aluminium alloys are easy to machine, their machinability is good. Next one, aluminium is an excellent conductor of electricity and heat. Aluminium alloys castings can be given an artificial wear resistant and corrosion resistant layer, so that is easy in the case of the aluminium castings. Next one, aluminium is non-magnetic. Aluminium is non-toxic, hygienic and physiologically harmless. Aluminium is an outstanding recycled material. So, these are all the advantages, in fact characteristics of aluminium. Now, these are the demerits of aluminium castorloys. High shrinkage, the shrinkage will be nearly 4 to 8 percent and it is highly susceptible to shrinkage defects and also shrinkage porosity. Now, it has the highest hydrogen what say absorb beauty, it absorbs hydrogen rapidly. Now, susceptibility to hot cracking as well as cold cracking, during solidification this hot cracking develops. Now, there is another cold cracking, cold cracking means during solidification it absorbs hydrogen and this hydrogen will be atomic hydrogen because of the what say high temperature. Now, during solidification this atomic hydrogen will become molecular hydrogen and as the solidification is progressing as the inter atomic spaces are reducing, the molecular hydrogen cannot be accommodated inside, thus it what say exerts pressure inside and that is how it results in cracking. So, this is the cold cracking, so it has the susceptibility to hot cracking as well as cold cracking and it has low ductility. Now, let us see that is why the pure aluminium may not be suitable for the casting purposes, but we can alloy it, we can add different alloying elements and we can make it useful for our what say casting purposes. Now, when we say alloying elements we can see there are 4 types of additives are there. First one is the major alloying elements typically include silicon, copper and magnesium. So, these are the major alloying elements in aluminium, next one there will be minor alloying elements. So, these are nickel tin, so these are found largely in alloys that are likely to that likely would not be high in the integrated die castings. Next one apart from the major alloying elements and minor alloying elements there will be microstructure modifying elements means what is the purpose we are what say modifying the microstructure. So, these include titanium, boron, strontium, phosphorus, beryllium, manganese and chromium. So, we add these elements extremely small amount, so that the composition is almost unaltered, but it will be changing the microstructure. Next one there will be impurity elements, what are these impurity elements means these are the elements coming in what say through the aluminium without our knowledge and without our intention. So, such elements are called as the impurity elements or they are also known as the residual elements. So, these typically include iron, chromium and zinc, so iron is the most common what say impurity element in the aluminium, next is the chromium and also the zinc. So, these are the four types of the additives that we can see in the aluminium castings. First we will see the major alloying elements, next we will see the minor alloying elements, next microstructure modifying elements, next we will see the effects of the impurity elements, first we will see the major alloying elements. Now, among the what say major alloying elements first one is the silicon, silicon is the what say most what say used alloying element, it is the number one major alloying elements in the aluminium castings. Now what is its role, silicon so high heat of fusion contributes immensely to annoy alloys fluidity or fluid life. Now it has got the high heat of fusion means what happens during solidification, during the phase change it liberates lot of heat. Now because it is liberating lot of heat what happens, it is what say temperature of the alloy will be increasing that is how the fluidity will be increasing, as the temperature is increasing fluidity will be increasing, so silicon contributes to the fluidity of the aluminium alloy. Next one it is limited solid solidity maximum will be 1.65 and formation of a eutectic with aluminium at a significantly high level 12 percent results in large volume fraction of isothermal solidification. This helps in avoiding hot tearing or hot cracking issues, so silicon is not only increasing the fluidity but it is also helping us to what say prevent the hot cracking. Next one thermal expansion of silicon is very low, hence the more silicon an alloy contains the lower is its thermal expansion coefficient. Most of the times what happens as the what say we pour the molten metal what happens if the what say thermal expansion of the alloy is high what happens the mould cavity may break because of the high thermal what say expansion of the alloy. But because of the silicon the thermal expansion will be minimum that is how there would not be any what say mould damage. Next one there are other roles made by the silicon, silicon forms a very hard phase if we see the silicon it is a very hard material, thus it contributes significantly to an alloys alloys wear resistance because it is very hard when we mix this hard silicon in the aluminium melt what happens it improves the wear resistance of the alloy. Next one silicon combines with other elements to improve an alloys strength and make alloys heat treatable. Next one silicon can cause a permanent increase in a castings dimensions termed growth if the part is not thermally stabilized before being put into elevated temperature surveys. Next one the other what say major alloying element of aluminium is the copper. Now what is the role of copper on the properties of aluminium alloys. Copper offers highest strength and hardness to the aluminium alloys. So the most commonly used what say alloy is the juralumin it contains copper why the juralumin is very hard and strong because it contains copper. It improves machinability on the downside copper generally reduces the corrosion resistance. Aluminium copper alloys do not contain silicon hence the fluidity decreases. Next one are the next major alloying element is the magnesium. Now what is the role of magnesium on the properties of aluminium alloys. Magnesium combines with silicon to form the hardening phase magnesium silicate you see MG2 SA. So this is a very hard phase because of that what happens the what say what say develops good strength and also wear resistance. This hard phase provides strengthening and heat treatment basis for the aluminium silicon alloys popularly known as the 356 family of alloys. Next one this hard phase also provides strength to the aluminium magnesium alloys. So magnesium typically what say forms the hardening phase thus it what say induces strength to the alloy. Now we have completed the major alloying elements of the aluminium. Next we will see the minor alloying elements. Among the minor alloying elements the first minor alloying element is the nickel. Nickel enhances the hard strength and hardness of aluminium copper alloys. It is employed for the same purpose in some aluminium silicon 3xx alloys but its effectiveness in the silicon containing alloys is less dramatic. Next one another minor alloying element is the tin. What is its role tin in aluminium tin alloys. So these are popularly known as 8xx series we will see later. Now the what say this tin reduces friction right in bearings and bushing applications. The tin phase in those alloys melts at a very low temperature at about 227 degrees. Now then what happens tin exduces under emergency conditions to provide short term liquid lubrication to rubbing surfaces if such bearing bushings severely over heating surface. So this is the greatest advantage of using in the bearings. So this tin is used for the bearing applications in the in the manufacture of the bearings. Now what happens in the bearings one part will be rubbing over another part. So most of the times we use the lubricants now okay fine sometimes this lubricant may be exhausted or there may not be any lubricant what will happen then heat will be developed now the one part will be rubbing over another part what will happen finally the parts will be damaged severely. At such times what happens this tin exduces under emergency conditions and it will be supplying few drops minor drops of liquid tin at the what say rubbing surfaces then it causes the lubrication between the rubbing parts. So this is the greatest advantage of tin. Next one so far we have completed the major alloying elements and the minor alloying elements. Next we will see the microstructure modifying elements. Among the microstructure modifying elements the popular what elements are the titanium and boron and what are their roles titanium and boron are used to refine primary aluminium grains. Initially if we do not use any what say modifier the grain will be very coarse when we use this what say modifiers like titanium and boron we get a very fine what say grain structure. Titanium alone added as a titanium aluminium mastoloid forms Ti Al3 you see which serves to nucleate primary aluminium dendrites. More frequent nucleation means large number of smaller grains. Now you can you we can see here this is the unrefined grain structure and here this is the refined grain structure. This refined grain structure offers us better mechanical properties that is why there is a need to add microstructure modifying elements. Next one Rhone of strontium, sodium, calcium and antimony. So these are also they are also come under the microstructure modifying elements. So these elements one or another but not in combination only one should be used at a time or added to eutectic or hypo eutectic aluminium silicon casting alloys to modify the morphology of the eutectic silicon phase. And with one of the above elements say you see the proportion 0.01 to 0.25% extremely small amount changes the eutectic silicon into a fine fibrous or lamellar structure and here this is the unmodified. So this is modified and this is super modified. So this what say microstructure modifying elements like strontium, sodium, calcium and antimony only one at a time but not in combination helps us to get a better what say microstructure with improved properties. Next one among the microstructure modifying elements the next what say elements are the manganese and chromium and what are their roles? Manganese and or chromium cause a beneficial change to the morphology of iron phases with large concentrations of iron manganese and chromium can minimize shouldering of the cast melt to steel tooling during die casting. So in the die casting applications so there is a drawback called shouldering means there will be metallic dyes will be used so the molten metal will be sticking to the metallic dyes. So this is the shouldering so this problem can be minimized when we use these what say modifying elements like manganese and chromium. Next one the last additives these are the impurity elements or these are also known as the residual elements among them the first one is the iron and what is its role? Iron is present in most of the traditional aluminum alloys as an impurity means it comes into the alloy without our knowledge and without our intention yet it is very useful impurity though it is coming into the alloy without our knowledge and without our intention it gives us some benefits. Iron in the concentrations of say you see the concentration may be 0.08 this is the normal composition at the most it will be 1% or more greatly it reduces the tendency of an alloy to shoulder to the die casting tooling. Again say there is a drawback this shouldering defect can be reduced in the die casting iron also reduces the tendency of hot tearing. So again hot tearing or the hot cracking another drawback in the aluminum castings so this aluminum which comes into the alloy as an impurity element or as a residual element minimizes the hot tearing. Next one another impurity that is the zinc. Zinc is present nearly as an acceptable impurity element in many secondary scrap based die casting alloys as such zinc is quite neutral it is neither enhance it neither enhances nor detracts the alloys properties. The only intentional and controlled additions of zinc to aluminum casting alloys are in the 7XX series. So these alloys are not yet suitable for the die casting or any of its variations. Only in one case that is the 7XX series we will be seeing these later within few minutes right. So in those series this is intentionally allowed or intentionally added for obtaining certain properties. Now let us see the classification of aluminum casting alloys we have seen the different what say alloying elements the major alloying elements the minor alloying elements what say microstructure modification elements and the what say impurities we have seen. Next are the how this aluminum alloys are classified and what basis now this is the classification of the aluminum cast alloys. Aluminum cast alloys are grouped based on the major alloying element present in that based on that they are classified. Aluminum greater than 99 percent is designated as 1XX series means so here it is mostly the pure aluminum 99 percent aluminum is present it is mostly the aluminum no other what say element is there no other major alloying element is there except few what say residual elements may be there or minor alloying elements will be there. So this is the 1XX series an aluminum alloy with copper as the major alloying element is designated as 2XX series in this series copper is the main alloying element. Next one an aluminum alloy with silicon with added copper and or magnesium is designated as 3XX series means in this series silicon is the main alloying element but it also contains little amount of copper or magnesium or both and this series is known as the 3XX series. Next one an aluminum alloy with silicon as the major alloying element in the previous case also silicon is present but along with silicon copper and magnesium are also present but here in the 4XX series one is silicon is the main alloying element. Now when the one is silicon is present as the main alloying element or the major alloying element it is designated as 4XX series. Next one an aluminum alloy with magnesium as the major alloying element is designated as 5XX series here the major alloying element is magnesium next there will be one unused series will be there 6XX series so this is not used till now. Next one an aluminum alloy with zinc as the main alloying element with small additions of copper, magnesium, chromium, manganese or combinations of these elements is designated as 7XX series here zinc is certainly is the major alloying element but it also may contain small additions of copper, magnesium, chromium or manganese or combinations of this. Next one an aluminum alloy with tin as the major alloying element is designated as 8XX series here tin is the major alloying element again there is another unused series 9XX series it is not used so this is the what say basis for the classification of the aluminum alloys. So aluminum alloys are classified based on the major alloying element and they are designated different series. Now this is the classification right so what say a conclusion as per the American National Standards Institute ANSI again we will see how they are classified 1XX series means it is almost the pure aluminum except that there will be what say little amounts of residual elements and minor alloying elements 1XX are the pure alloy what say pure aluminum next one 2XX series are the what say copper based aluminum alloys copper is the main major alloying element in the 3XX series silicon is the what say major alloying element along with silicon magnesium or copper or magnesium or copper will be present in the 4XX series only silicon is the main alloying element major alloying element in the 5XX series magnesium is the main major alloying element in the 7XX series zinc is the major alloying element in the 8XX series tin is the main alloying element. So we can see so these are the codes we can later we will see different types of what say designations like 3, 5, 6 the most popularly used what say aluminum alloy so each what say these numerals will be interpreting some information. Now let us learn about 1XX series alloys in the 1XX series aluminum is 99% minimum there must be 99% aluminum sometimes it will be even more than 99%. Now the second two digits one means certainly it is the what say 99% aluminum is there no doubt in that the second two digits indicate the minimum aluminum percentage when expressed to the nearest what say 0.01% for example you see there may be a series like say 100.1 so this is the designation of an alloy what does it mean it means the aluminum means what say 99% aluminum again sometimes there may be a what say grade 170.1 what does it mean already 1 is there 99 definitely it will be there what is this 70 means 99.70% aluminum the last two digits indicate the product form again we can see this ones are there like 0.1 here we can see right sometimes 0 will be there what is the meaning right for example 1XX 0.0 is for castings and 1XX 0.1 is for the ingots 0 means it is for the castings and 1 means it is for the ingots next let us see the 2XX series to 8XX series first digit indicates the main alloy increment starting from 2 to 8 first what say digit indicates the main alloy increment from 2XX through 8XX alloy designations the second and third digits have no numerical significance but serve only to identify the various alloys in the group then the second what say digits they may not indicate the exact proportion of the alloys but they will tell us about the other alloying elements the presence of the other alloying elements again not only what say we can see 2XX will be there 3XX will be there 4XX say till 8XX series are there of course 0.2 0 will be there decimal and 0.1 will be there 0 means casting 1 means ingot now these are the suffixes now there will be prefixes will be there like A A 3 5 6 likewise there will be A will be there B will be there what is the meaning letter A indicates the first modification of the original alloy similarly letter B indicates the second modification of the same alloy and so on. Modifications indicate changes in the original alloys chemical compositions so these are the information about the 2XX to 8XX series now first let us see let us learn about 2XX series something more in this the 2XX series aluminum copper alloys the majority of aluminum copper alloys grades contain 4 to 5 percent copper certainly one someone says that the alloys designation is 2XX something means it is the major alloying element is copper because 2 is present now what is the proportion the proportion of copper will be 4 to 5 percent for example so these are the important alloys important 2XX series say 201.0 208.0 222 222.0 likewise so these are the important series now what are the applications of the 2XX series cylinder heads for automotives and aircraft engines pistons for diesel engines exhaust system parts and many more so these are used in the automotives so this is the chemical composition of some 2XX cast alloys and here we can see this is the designation 201.0 208.0 222.0 now these are the alloying elements silicon copper manganese here it is zinc and titanium and here we can see this is the 201 and silicon is 0.1 maximum and this is the major alloying element 4 to 5.2 and in the case of the 208.0 silicon will be 2.5 to 3.5 and remember in this series the copper is the major alloying element and its proportion will be 3.5 to 4.5 again 222.0 maximum silicon will be 2 percent and the copper will be 9.2 to 10.7 percent and there will be other elements like zinc and titanium so these are the this is the what say microstructure modifying element and balance is the iron in the what say triplex what say 3XX series means what does it mean the major alloying element will be silicon along with magnesium and copper you can see here aluminum silicon magnesium and copper silicon is definitely present along with silicon either magnesium or copper sometimes both the majority of these alloys grades contain 6 to 10 percent silicon 0.2 to 0.5 percent magnesium and 0.25 to 4 percent copper important to alloys in this 3XX series are say 319.0, 320.0, triple 3.0, 356.0 so this 356 is very popular and what are the applications automotive cylinder blocks, car wheels, aircraft fittings, casings and other parts of compressors and pumps so these are the typical what say applications of 3XX series and here we can see so this is the chemical composition of some what say 3XX alloys designation is say triple 3.0 and this is the silicon will be present from 8 to 10 percent copper will be present 3 to 4 percent, magnesium 0.5 maximum, magnesium 0.05 to 0.5 percent zinc 1 percent is the maximum titanium 0.25 percent and 356.0 silicon will be 6.5 to 6 percent 7.5 copper 0.25 maximum, magnesium 0.35 to 0.35 is the maximum and again it contains magnesium 0.2 to 0.45 zinc 0.35 maximum and titanium 0.25 maximum. Remember in this series 3XX series silicon is the major alloy increment not only silicon along with silicon copper and magnesium are also present either copper or magnesium are both and the balance is aluminum. Next one 4XX series 4 means the majority of these alloys contain 4 to 13 percent silicon here the once 4 is present the major alloying element is silicon and the silicon proportion will be 4 to 13 percent and what are the important alloys in this series 413.0, 443.0 and so on and what are the applications? Pump casings, cookware, thin wall castings likewise and remember here thin wall castings can be produced successfully why because silicon is up to 13 percent. Silicon offers the what is a more maximum fluidity to the casting alloy why because during solidification it what is a releases latent heat of fusion because of that the fluidity will be enhancing that is how the thin wall castings can be successfully made using this series 4XX series. Now this is what is a chemical compositions of some 4XX cast alloys now here we can see this is the designation 413.0, 443.0 and the silicon composition is 11 to 13 percent copper 1 percent maximum, manganese 0.35 maximum magnesium 0.1 percent maximum, zinc 0.5 percent and in the 443 series silicon will be 4.5 to 6 percent copper 6 percent maximum, manganese 0.5 percent maximum, magnesium 0.05 percent maximum, zinc 0.05 percent maximum and titanium 0.25 percent maximum and remember in this series 4XX series the silicon is the major alloying element and the balance is aluminum. Next one 5XX series these are the aluminum magnesium alloys means magnesium is the major alloying element majority of these alloys grades contain 4 to 10 percent magnesium what are the important alloys 514.0, 518.0 and these are the what is a typical application chemical and sea base kitchen utensils and mostly sand castings chemical compositions of some 5XX cast alloys. So this is the designation 514.0 and 518.0, silicon will be 0.35 maximum, copper 0.15 maximum, manganese 0.35 maximum, magnesium 3.5 to 4.5, zinc 0.15 to maximum, titanium 0.25 percent maximum. In the 518.0 silicon will be 0.35 percent maximum, copper will be 0.25 maximum, manganese 0.35 percent maximum and magnesium 7.5 to 8.5, zinc will be present say maximum 0.15 and the balance is aluminum. Remember in this 5XX series magnesium is the major alloying element. Now let us see the 7XX series what is the 7XX series the majority of these alloy grades contain 2 to 8 percent zinc. Zinc is the major alloying element. Now these are the important alloys like alloys 705.0, 713.0. Now these are the applications these are not suitable for high temperature applications due to rapid softening because zinc is present it means at a very low temperature. So it is they are not suitable for high temperature applications right. Sacrificial anode for steel structure protection. So these are used as the sacrificial anode for steel structure protection against corrosion. Next one marine castings right form machinery. So this zinc offers the resistance against corrosion. Now these are the chemical what is a compositions of some what is a 7XXX cast alloys, designation you see. So this is 705.0, 713.0. In the 705.0 silicon will be 0.2 maximum percent copper will there will be copper 0.2 maximum, manganese 0.2 4 to 0.6 percent, magnesium 1.4 to 1.8 percent, zinc 2.7 to 3.3, titanium 0.25 percent maximum and there will be other elements like chromium 0.2 to 0.4 percent. And in the 713.0 0.25 percent maximum silicon will be there and copper will be from 0.4 to 1 percent, manganese 0.6 maximum percent, magnesium 0.2 to 0.5 percent, zinc 7 to 8 percent and titanium maximum 0.25 percent will be there and the balance is aluminum. And remember zinc is the major alloying element in the 7XX series. Next let us see the 8XX series. So in this series tin is the major alloying element. Majority of these alloying grades contain 5 to 7 percent tin. Important alloys, alloys say 752.0. So this is the most important alloy. Now what are the applications? Mono metal, bimetal side bearings for internal combustion engines and other applications. These are the chemical compositions 852.0, silicon 0.4 maximum, copper 1.7 to 2.3, manganese 0.1 percent maximum, magnesium 0.62, 0.9, there will not be zinc and titanium 0.25 percent maximum and other elements like tin are the not other elements. So this is the major alloying element here. 5.5 to 7 percent and other alloying elements like nickel 0.9 to 1.5 percent and the balance is aluminum. Here in this series tin is the major alloying element. Now so far we have completed the aluminum castor alloys. Now let us see the magnesium castor alloys. Now the first question is why magnesium? It is the lightest structural metal. Its density is 1.8 grams per cubic centimeter whereas for aluminum the density is 2.7 grams per cubic centimeter. Here it is 1.7 means almost 1 gram less compared to the aluminum. Can be cast thinner and faster. Can be machined easier than aluminum. The better dimensional stability, high specific strength and high damping capacity, good thermal conductivity and 100 percent recyclability. So these are all the benefits compared to the aluminum alloys. That is why slowly magnesium alloys are replacing aluminum alloys. But pure magnesium is volatile at high temperatures. It is extremely corrosive in wet environments. Alloying with elements like aluminum, zinc, copper, etcetera will improve the properties. So at any cost we cannot use the pure magnesium. We have to alloy it with different elements like aluminum, zinc, copper and so on. Now these are the advantages of magnesium alloys. Castings can be made with thinner walls compared to aluminum. 1 to 1.5 mm, up to 1.5 mm can be made. Castings cool more quickly due to a reduced latent heat of fusion per unit volume. What is a solidification time is much lesser compared to aluminum. High what is a gate pressures can be achieved using moderate pressures due to the low density of magnesium. Mainly it is used in the what say die castings. So that time say during the pressure die casting we need to what say apply higher pressure. But when we use the magnesium even what say moderate pressure will be enough because why there is the density of the magnesium is low. Iron from castings casting dies has low solubility in magnesium alloys which reduces unit tendency to die shouldering. Now this is mainly used in the die castings. So what is the problem with the die castings? So in the die castings the dies are the ferrous alloys. Now what happens is the iron from the dies may react with the magnesium that would not happen here. In the case of the aluminum alloys it may happen but here it has got the low solubility that is how this shouldering defect can be minimized. Again now we will see the classification of the magnesium cast alloys. As per ASTM system the classification comprises 2 capital letters followed by 2 or 3 numbers. There will be 2 letters will be there. Again followed these 2 letters will be followed by 2 or 3 digits. The 2 capital letters stand for the 2 major alloying elements. The first letter indicates the highest alloying element and the second letter indicates the second highest alloying element. The 2 numbers after the 2 letters there will be 2 numbers will be there. These 2 numbers stand for the amount of the 2 major alloying elements. The first number stands for the percentage weight of the first letter element. Second number stands for the percentage weight of the second alloying element. Now different letters and their significances. In the what is the classification we will see for example EH at 91. What does it mean? Say aluminum will be the major alloying element, zinc will be the next major alloying element and 9 indicates the proportion of aluminum and 1 indicates the proportion of zinc. Like this several letters are used. We can see here that A means aluminum, B means bismuth, C means copper, D means cadmium, E means rarer metals, F means iron, G means magnesium, H means thorium, K means zirconium, L means lithium, M means manganese, N means nickel, P means lead, Q means silver, R means chromium, S means silicon, T means tin, W means yttrium and Z means zinc. EH at 91, this is the most popular alloy. The magnesium alloy contains you see aluminum. Here this is a magnesium alloy and aluminum is the main alloying element. Next one zinc is the second alloying element. The magnesium alloy contains 9 percent aluminum and 1 percent zinc. That is the meaning of EH at 91. Similarly QE 22, QE 22 what does it mean? It is a magnesium alloy. It contains 2 percent silver and 2 percent rarer metals. Means here QE is present that represents silver, presence of silver. E is there that represents the presence of rare metals, 2 percent silver and 2 percent rare metals. Next one AC 63. You see this is again a magnesium alloy. It contains 6 percent to here A. A means aluminum and it contains 3 percent copper. Now this is the direction of magnesium alloy development and this is the magnesium and here we can see as we what say add aluminum, magnesium sorry manganese it will be AM 50, AM 60 and here we will be adding aluminum, calcium and we can see here and rare metals zinc, manganese and here we will be adding aluminum, calcium, rare earth, magnesium, zinc and rare earth likewise. So this way when we what say mix the alloy measurements we get ductile what say alloys. And here we can see here we are adding aluminum and zinc and it becomes EH at 91 and here we are adding aluminum and silicon it becomes AS 21, AS 41. Here we are adding aluminum and rare earth metals it becomes AE 42 and here we are adding aluminum, calcium and so on. And here we are adding silver rare earth metals zirconium it becomes QE what say 22, EQ 21 and here we are adding yttrium rare earth metals zirconium and it becomes WE 54, WE 43. This side when we what say keep on alloying the elements here thus we will be getting creep resistance alloys. The alloys will have the very good creep resistance and here we can see here. So here we can see this what say ellipse indicates the high pressure die casting means these alloys are used for the high pressure die casting these alloys are also used for the high pressure die casting. But this one we can see this diamond is for the wrought alloys. So these are not the cast alloys. Again we can see this rectangle indicates the they are meant for the sand castings. These are the alloys here we can see this is one set and this is the another set. So these two groups they are useful for the sand castings and here we can see fiber and hybrid reinforced magnesium materials and if we keep like what say add like this we will be getting creep resistance alloys thermal expansion alloys and Young's modulus will be improved. Likewise we can improve the what say develop the alloys in three directions. Now magnesium alloys for automotive applications. So these are the die casting alloys age at 91 D it is the most widely used alloy next one AM 60 AM 50 AM 20 these are the higher ductility alloys next one AE 42 AS 41 AS 21. So these are the higher temperature alloys next one ZE 41 AC 63 these are the heavy duty and high temperature alloys age at 91 D alloy properties good room what say temperature strength excellent die castability and good corrosion resistance. What are the applications? Steering column brackets four wheel drive transfer case manual transmission case clutch pedal brake pedal steering column brackets crank case chain housing steering box rear link arms and sub frames and so on. So these are the applications of age at 91 D alloy next one let us see the applications of AM 60 AM 50 and AM 20 alloys these are what are the properties they have high ductility good impact strength good die castability and good corrosion resistance and what are the applications? Seat frames wheels instrument panels and so on next one AE 42 AS 41 and AS 21 alloys what are the properties? Good strength and creep resistance at temperatures above 120 degree centigrade but poor castability applications automatic transmission case next one ZE 41 AC 63 alloys what are the properties? Sand castings good what say room temperature strength and improved castability and applications so these are used for making the what say engine blocks. Friends in this lecture we have seen different what say aluminum alloys and different aluminum cast alloys and different magnesium cast alloys and we have seen what say how the aluminum cast alloys have been what say classified they are classified based on the major alloying elements the 1 xx series, 2 xx series and so on and we have also seen how the magnesium what say cast alloys have been classified like AZ 91 and so on again so this AZ 91 remember so there will be 2 letters will be there these 2 letters indicate the 2 main alloying elements and there will be 2 digits will be there these 2 digits will be reflecting the or indicating the proportion of the 2 alloying elements likewise so there will be different classifications of the magnesium alloys will be there we have seen and now a days slowly the magnesium alloys are replacing the aluminum alloys why because the density of magnesium alloys is what say lesser than the density of the magnesium alloys and their castability is very high even very thin sections can be made so that is how magnesium alloys are gaining more and more importance these days but the problem is with the magnesium alloys while melting right so the melting has to be done very carefully the magnesium can explode if it is melted in a open atmosphere that is why always the magnesium is melt what say melted in a closed environment closed and controlled environment that is how the melting of magnesium becomes becomes expensive no problem it may become little expensive compared to the melting of aluminum but the properties of magnesium alloys are much better compared to the properties of aluminum alloys so in the next class we will be seeing other what say nonferrous cast metals until then thank you and goodbye.