Magnesium Alloys
Today we will discuss about different types of non ferrous alloys so the first metal that we are going to discuss is magnesium. We will discuss about magnesium alloys. Most important property of magnesium is it's very low density. Magnesium is just 1.7 gram per cubic centimeter, aluminium on the other hand was 2.7 gram per cubic centimeter iron is close to 7 point 5 gram per cubic centimeter. So magnesium is practically one of the least dense metal that exists. Magnesium alloys have hexagonal cubic system structure and it is relatively soft metal. It is quite a soft metal. The problem the HCP structure since it has effectively only three slip systems makes it quite difficult to deform. So magnesium is not easily deformable this is the main point of concern in using magnesium alloys. Since many applications require deformation to make the end product. Thereby a lot of research is going on in the field of magnesium alloys in order to create something which is easily deformable. So magnesium alloys are being researched to improve its deformation properties. The problem with its deformation leads to fabrication by casting or hot working casting, is basically liquefying the magnesium alloy that is making it liquid and then casting it into the end-product shape hot working. How does that help increasing the temperature? Two high temperature leads to a better deformable properties. It can be deformed easier than at room temperature.
So fabrication process is normally carried out by casting or hot working similar to aluminium magnesium also has a very low melting point. Aluminum had 660 degree Celsius melting point, magnesium had fire has 651 degree surface melting point quite similar. Magnesium is a very reactive metal. Thereby if you expose magnesium to air and it is slightly high in temperature if it is heated then it catches fire instantly. So it's better to avoid exposing magnesium to heated air or exposing heated magnesium to air either way it can catch fire. Magnesium easily corrodes this is a big disadvantage under marine conditions. Therefore magnesium should be avoided from being used under marine conditions it can easily corrode. Now the alloying elements that are normally used for magnesium alloys is aluminium, zinc, manganese and some rare earth metals. Some rare earth elements are also used these are the main allowing elements and the magnesium alloys are either cast or wrought cast means liquefied and shaped. Finally wrought means it can be treated by different deformation processes. So the alloying basically improves the deformation behavior slightly and thereby it can be even either cast or wrought.
Titanium Alloys
Now let us see the next kind of allowing system that is titanium alloys. Titanium has also a low density relative to iron not as low as aluminium or magnesium. It has a density of 4.5 gram per CC. Advantage of titanium contrary to aluminum and magnesium which had a very low melting point. The melting point of titanium is quite high, it is 1668 degree Celsius which is actually very high even higher than iron in addition to that titanium has a very high Young's modulus. The Young's modulus for titanium is 107 Giga Pascal which is very high. Thereby in titanium alloys are extremely strong and the ultimate tensile strength for titanium alloys can be as high as 1400 mega Pascal.
Titanium alloys is also very ductile and easily malleable. So the good properties is it is strong as well as ductile has a very high melting point. The drawback is that it has chemical reactivity is high at elevated temperature. So this is a negative the chemical reactivity increases at high temperature. This is a positive property another positive property is at room temperature very good corrosion resistance. So this is also a positive property the corrosion behavior of titanium alloys is good at room temperature. Main drawback of titanium alloys is that it is very costly. Therefore the titanium alloys is only used in very specialized cases. So just to recap the positives are extremely strong ductile and machinable very good corrosion resistance, negatives chemical reactivity is high at elevated temperature and quite costly. Thereby titanium alloys are mainly used in scenarios like airplane structure specialized applications, spacecraft against the slice application implants. Body implants can be made out of titanium alloys again a specialized application.
Refractory Metals
The refractory metals as the name suggests refers to metals which has very high melting point. So some of the examples of refractory metals are nabhi 'm which has a melting point of 2468 degree celsius, moly bit gnam 2623 degree celsius, tantalum 3020 degree celsius and the highest melting point metal known tungsten which has 3410 degree celsius. So as you can see this melting point of these metals are very drastically high compare this to the melting point of aluminum which was 660 degree Celsius, compare this to even the melting point of titanium which was quite good at 1668 degree Celsius. But these are even better than those and thereby these metals have special applications under high temperature condition. Now what is it that gives such a high melting point for these metals. The fact is that they have very strong interact maquon dings. The bond strength for these metals are very high. In addition these refractory metals have large elastic moduli, high strength as well as very high hardness. The very high hardness is a manifestation of the strong inter atomic bonding and these properties even exist at elevated temperature. The idea that the properties remain good even at elevated temperature makes them very appropriate to be used at high temperatures.
Now refractory metals as such can have varied uses, but the most important fact is that their high melting point make them very suitable for high temperature application. So mainly they are used for high temperature condition applique. Now tantalum and molybdenum is also added to steel as a alloying element in order to improve corrosion behavior. These four refractory metals are also added as alloying elements in super alloys which are then used in aircraft industry. So these have specialized application to where fracture metals are basically used under conditions where they will be exposed to high temperature like aircraft industry. In scenarios where the temperature might go very high like the rocket nozzle, where the temperature is very high at entry or exit due to high frictional forces. So under such circumstances what happens is refractory metals come into play. In addition to ceramics which we did not discuss in details. So this brings us to the end of our discussion about non ferrous alloys.
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