![]() Their stability (at high enough temperatures) against phase separation and formation of intermetallic phases was explained by the high mixing entropy, which could be achieved if the number of elements was large enough and the stoichiometry close to equiatomic. What are HEAs? Originally they have been defined as homogenous alloys composed of 5–13 major elements with concentrations between 5 and 30 at.%, and with simple average crystal structures such as cF4-Cu ( fcc), cI2-W ( bcc) or cP2-CsCl. The interest in these alloys has especially increased for the last 5 years. Starting from 2002 until now, almost 400 papers have been published where the term “high-entropy alloys (HEAs)” is used ( Figure 1), in most cases with the focus on microstructure and mechanical properties. ![]() ![]() The literature overview is complemented by own studies demonstrating that the alloys CrFeCoNi, CrFeCoNiAl 0.3 and PdFeCoNi homogenized at 13☌, respectively, for 1 week are not single-phase HEAs, but a coherent mixture of two solid solutions. In contrast to classical multielement/multiphase alloys, only single-phase multielement alloys (solid solutions) represent the basic concept underlying HEAs as mixing-entropy stabilized homogenous materials. In our paper, we focus on probably single-phase HEAs (solid solutions) out of all HEAs studied so far, discuss ways of their prediction, mechanical properties. Since then many equiatomic (or near equiatomic) single- and multi-phase multicomponent alloys were developed, which are reported for a combination of tunable properties: high hardness, strength and ductility, oxidation and wear resistance, magnetism, etc. ![]() The term “high-entropy alloys (HEAs)” first appeared about 10 years ago defining alloys composed of n=5–13 principal elements with concentrations of approximately 100/ n at.% each. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |