Abstract
Metal has always been a crucial part of human society with prestigious status in the field of material science development history. However the abundant research done on metal and alloy also resulted in the lack of marginal breakthrough in modern days. During last decade, a brand new alloying system called “High Entropy Alloys” (HEAs) was presented and gradually gaining attention from all associations, its special mechanical properties and element composition has dawned a new era of alloy materials. Due to apparent differences of formation rules between HEAs and traditional alloys, current researches toward HEAs are still far from successfully providing results to explain the core effect and compositional theory of HEAs. This research was done on a series of FCC alloys consists of traditional low-entropy NiW alloys, medium-entropy alloy NiCrFe and HEA NiCrFeMnCo by conducting mechanical and structural experiment respectively in both macro and micro scales. Macro scale experiments included Vickers hardness and density measurement. Micro scale experiments included nano indentation, in-situ SEM micro pillar compression and in-situ TEM nano pillar compression, respectively performed on (100), (110) and (111) crystal planes of alloys with different entropy status. Micro scale crystal structure differences between traditional alloys and HEAs was obtained via high intensity X-ray diffraction. By analyzing mentioned experiment results with theoretical information, we found numerous distinct differences in both deformation behavior and crystal structure between traditional alloys and HEAs, providing further insight for future study of HEA’s core effect and compositional theory.