Thermal stability of nanocrystalline Al−10Fe−5Cr bulk alloy

Abstract

Abstract Thermal stability of nanocrystalline Al−10wt.%Fe−5wt.%Cr bulk alloy was investigated. The initial micro-grained mixture of powders was processed for 100 h using mechanical alloying (MA) to produce nano-grained alloy. The processed powders were sintered using high frequency induction heat sintering (HFIHS). The microstructures of the processed alloy in the form of powders and bulk samples were investigated using XRD, FESEM and HRTEM. Microhardness and compression tests were conducted on the bulk samples for evaluating their mechanical properties. To evaluate the thermal stability of the bulk samples, they were experimented at 573, 623, 673 and 723 K under compression load at strain rates of 1×10−1 and 1×10−2 s−1. The annealed samples exhibited a significant increase in their microhardness value of 2.65 GPa when being annealed at 723 K, as compared to 2.25 GPa of the as-sintered alloy. The bulk alloy revealed compressive strengths of 520 MPa and 450 MPa at 300 K and 723 K, respectively, when applying a strain rate of 1×10−1 s−1. The microstructural stability of the bulk alloy was ascribed to the formation of iron and chromium containing phases with Al such as Al6Fe, Al13Fe4 and Al13Cr2, in addition to the supersaturated solid solution (SSSS) of Cr and Fe in Al matrix.