Insights into micro-mechanical response and texture of the additively manufactured eutectic high entropy alloy AlCoCrFeNi2.1

Abstract

In the present study, the evolution of microstructure, texture and high-temperature mechanical behavior of the additively manufactured (AM) eutectic high entropy alloys (EHEA) AlCoCrFeNi2.1 have been investigated. The material was manufactured through laser engineered net shaping (LENS) process. The microstructural investigation revealed constituent phases consisting of dendritic and eutectic features, with the phases having ordered FCC (L12) and BCC crystal structures. The phase fraction of L12 was more across the build (X) face and that of the BCC was more along build plane (Z face). In both the phases, nickel constituted the base element with L12 phase being deficient in Al and the BCC deficient in Cr and rich in Al. The stability of L12 phase was attributed to Co, Cr, and Fe with near equiatomic distribution. Kurdjumov-Sachs (KS)orientation relationship was followed between the ordered L12 and BCC phases along and across the build-up direction. Strain partitioning was observed more in the BCC phase than in the L12 phase during uniaxial compression at all temperatures. Difference in hardness was observed along Z and X directions which further resulted in yield anisotropy during compression test at room temperature. High-temperature compression tests at temperatures 400 °C, 600 °C, 700 °C, and 800 °C revealed that the yield strength increased from room temperature till 400 °C and then started decreasing till 800 °C.