Microstructure and compressive properties of AlCrFeCoNi high entropy alloy

An AlCrFeCoNi high entropy alloy was prepared by vacuum arc melting. Only diffraction peak corresponding to a BCC crystal structure is observed for this AlCrFeCoNi high entropy alloy. The microstructure of this AlCrFeCoNi alloy is polygonal grains with intragranular dendritic segregation. Dendritic segregation area is found to be Al, Ni rich and Cr, Fe deplete, while interdendritic segregation area is Cr, Fe rich and Al, Ni deplete. The distribution of Co is essentially identical. The fine microstructure of dendritic segregation area and of interdendritic segregation area is found to be nanoscale spherical precipitates morphology and basket-weave morphology, respectively. Results of EDS attached on high resolution scanning electron microscope (SEM) revealed that these morphological characteristics are also resulted from elements segregation. This AlCrFeCoNi high entropy alloy exhibits excellent compressive properties. The yield stress, compressive strength and plastic strain of the alloy reaches 1250.96, 2004.23 MPa, and 32.7%, respectively. The fracture mechanism of this AlCrFeCoNi high entropy alloy is observed as cleavage fracture and slip separation. (C) 2008 Elsevier B.V. All rights reserved.