高熵合金显微结构的热力学分析_英文_.docx

Volume 42, Issue 2, February 2013Online English editi Volume 42, Issue 2, February 2013 Online English edition of the Chinese language journal Thermodynamic Analysis for Microstructure of High-Entropy Alloys Pi Jinhong1,2, Pan Ye1 1 Southeast University, Nanjing 211189, China; 2 Nanjing Institute of Technology, Nanjing 211167, China Abstract: The Gibbs free energy of liquid and crystal, intermetallic compounds, and amorphous phases were investigated by ther- modynamic analysis for microstructure of high-entropy alloy (HEA). Results show that the value of ΔSrΔHh(sol.) plays an important role in estimating the microstructure of HEAs. The alloys with lower value of ΔSrΔHh(sol.) have stronger tendency of forming single fcc or bcc solid solution, and the alloy with complicated microstructure always has larger value of ΔSrΔHh(sol.). Key words: high entropy alloys; microstructure; thermodynamic properties High-entropy alloys (HEAs) with multiple principal ele- ments in equimolar or near-equimolar ratios have been ex- plored by Yeh et al[1,2]. Compared with conventional alloys with one or two major constituents, such as steels and amorphous alloys, HEAs contain more than five elements as major constituents and other minor elements used for enhanc- ing some definite properties[3]. In the past decade, most reports on HEAs systems showed that these alloys were composed of simple fcc and/or bcc solid solutions with varying concentra- tions of each principal element[4,5]. Strong tendency of forming nano-scale precipitation and amorphous structure, predomi- nant properties in high hardness and compressive strength, superior resistance to temper softening, super wear resistance, wonderful corrosion resistance[1-5] etc made HEAs very prom- ising alloys. Researchers owed the simple microstructure of HEAs to high mixing entropy or configuration entropy (ΔS). However, systemic analysis revealed that large a value of ΔS did not always ensure simple microstructure. For example, both Al