Understanding microstructure and mechanical properties of(AlTa0.76)xCoCrFeNi2.1 eutectic high entropy alloys via thermo-physical parameters

• 作者: Min Jung Kim Gyeol Chan Kang Sung Hwan Hong Hae Jin Park Sang Chul Mun Gian Song Ki Buem Kim
• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2020,（22）
• 页码范围: 131-137
• 页数: 7页
• 语种: 英文

摘要

(AlTa0.76)xCoCrFeNi2.1 (x values in molar ratio,x =0.1,0.3,0.5,0.7,1.0,and 1.5) alloys were designed to investigate the microstructure and mechanical properties of the eutectic high entropy alloys (EHEAs)consisting of FCC,B2,and Laves phases.Depending on the compositional variatio,clear microstructural variation was observed,as follows:(1) Group 1 :FCC dendrite + Laves interdendrite (x =0.1),(2) Group 2:FCC dendrite + fine-eutectic structure consisting of FCC and Laves phases (x =0.3,0.5 and 0.7),(3) Group 3:B2 dendrite + bimodal eutectic structure[FCC/B2 +Laves](x =1.0),(4) Group 4:Laves dendrite + eutectic structure consisting of B2 and Laves phases (x =1.5).As the fraction of Laves or B2 phases increases,yield stress increases from 293 to 2336 MPa,while the plastic strain decreases from 50 ％ to 2％.Thermo-physical parameters,such as mixing entropy (△Smix),mixing enthalpy (△Hmix),valence electron concentration(VEC),and atomic size difference (δr),were calculated to understand the microstructural variation.Two criteria (δr-VEC and δr-△Hmix) were utilized to elucidate the formation of the eutectic structures in the present EHEAs,revealing the usefulness of the thermo-physical parameters in the development of EHEAs.