The microstructure and phase equilibrium of new high performance high-entropy alloys

• Published in: Journal of alloys and compounds 2009-08, Vol.483 (1), p.209-212
• Main Authors: Hsieh, Ker-Chang, Yu, Cheng-Fu, Hsieh, Wen-Tai, Chiang, Wei-Ren, Ku, Jin Son, Lai, Jiun-Hui, Tu, Chin-Pan, Yang, Chih Chao
• Format: Article
• Language: English
• Subjects: Applied sciences; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Disordered systems; Exact sciences and technology; High temperature alloys; Joining, thermal cutting: metallurgical aspects; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Metals. Metallurgy; Physics; Precipitation; Treatment of materials and its effects on microstructure and properties; Tribology and hardness; Welding
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2008.08.118

In recent years, series of high-entropy alloy have been well developed with high hardness and high temperature stability. These properties could apply in hard surface welding technology. Several AlCrFeMnNi high-entropy alloys have been developed and made as welding rods to apply in the hardface welding on carbon steel using nickel-based alloy as bond coating layer. The hardness of hardface can reach Hv 900 after aging at 700 °C for 4 h. One of alloys performed resistant with the thermal effect during hardfacing operation and maintain better hardness in the multiple overlays. An electron probe microanalyzer (EPMA) was used to verify the phase compositions of hardfacing microstructure. There is nanoprecipitate phase formed within the matrix grain and might contribute the high hardness. A primitive phase diagram calculation was done by using the Calphad method. The calculated results show that the hardening mechanism is due to bcc order/disorder coherent strengthening within the matrix grain. Two high-entropy alloys were equilibrated at 700 °C for 10 days. The equilibrium phases are consistent with the calculated isopleth. The new phase may relate with FCC phase structure and still under investigation.