Question

Engineering materials are often placed in various service conditions, such as different status of mechanical stresses and temperatures.

High-temperature alloys (or superalloys) are an exceptional class of engineering materials for the applications at elevated temperature. Discuss the effect of the grain size on the high-temperature performance of superalloys and suggest how to strengthen the high-temperature superalloys.

With a detailed explanation

Answer 1

AnsSuper Alloys: . Suber alloys are high strength alloys that are basically used for high temperature and high speed oplolidatima These are Ni, Co 6 Niore based orpoys are hare been extensively used in Acroscope i power, industries and power-parant industries.' * Effect of the grain size on the high- temperature at the performonce of Superollays in following ways: At high temperature (equal to or in exces of - 850°c), the groin size Controls the creep properties. Groin size con play a major role in Can Holling creep resistance Groin size has the opposite effect at high tem pesoture thon at ambient Conditions. - horge Arain size increases Coeep resistonce hence the use of single coystop where feasible, especially for supesarlays, At edevoted temperature, effect of groin sine for the tensile strength of alloy : An care of course groin-size, the difference between the tensile strength and yield strength was closer. However, in case of the fine groin size, the difference value between the Ansile strength and yield strength was bigger thom that of Coarse groin size.

# How to strengthen the high temperature Supereepoys → Oxidation and corrosion resistance is provided by the formation of a protective oxide doyer, which is formed when the metol is exposed to oxygen. We con protect rest of the component of Superocloys through the foomotion of secondooy prose precipitates such as gamma boime and 'Carbides Troough precipitation strengthening . We can strengthen the high - temperature Seberapays. there are also three strengthening mechoniem used to improve the Righa temperature peoformance of super alloys: I ca solid solution strengthening ( Poecipitation foodening c) Gooln boundary strengthening, Solida solution strengthening - > hi mec amito, imლადding the. (ბელთუქრიჩთ of impurity result in increase in yield strenyih. Alloysis stronges thom pure netop because >> ulogu impusity atoms that go into the solid solution impore l'office stoins on the surrounding hoce otom

hottice stain field interaction b/w alislocation and these impurities atoms nesult: oliklocation movement i estricted which is flengthen the alloys. *S Precipitation hordening In this Mechanism, alloy is heared to a hesatire obore the solves line into the ai lorose and held for a period sufficient te dressive (B) Beto phone . Quenctions to coom temperature to creare e supersequroled solid solution. Precipieton treatment : Allog is heared to o temperature below to to cause precipitation of fine postide of pe to share - 10 femper otare solution heat treatment Quener + precipitation heat Heament Time