EXPERIMENTAL DETERMINATION OF STACKING FAULT ENERGY FOR HIGH ENTROPY ALLOYS

Abstract

High entropy alloys are multicomponent equiatomic alloys that form simple solid solutions. It shows higher strength and ductility and many more good properties. HEAs are used at very low temperature (cryogenic temperature) as well as high temperatures. HEAs are used in structural application due to these properties. The reason of these good properties is stacking fault energy. Low stacking fault energy materials like Cu-30% Zn, Cu-9% Ge shows higher strength and it is used in structural application. In these materials, ductility is low, that’s why we are using HEAs. We report in this thesis, experimental methods for determination of stacking fault energy by X-ray diffraction methods for four and five component HEAs. Samples were prepared by combinatorial magnetron sputtering process for getting gradient samples. After that various characterization are done on these samples like X-ray diffraction for phase analysis and staking fault energy determination, energy dispersive x-ray spectroscopy for composition analysis, scanning and transmission electron microscopy for grain size determination and finally nano indentation for Young’s modulus and hardness measurements. We are reporting two methods for stacking fault energy determination. First method is analytical method and second is using software (PM2K). We show the increase in stacking fault energy on increasing Ni content in samples. We are also showing that the Young’s modulus and hardness value decreases on increasing stacking fault energy.