Microstructure and Sintering Behaviors of Al-Cr-xSi (at.%) System Alloys Processed by Spark Plasma Sintering

In this study, microstructure and sintering behaviors of the gas-atomized Al-(25 or 30) Cr-xSi alloy (x = 5, 10 and 20 at.%) during spark plasma sintering (SPS) process were investigated. Gas-atomized alloy powders were manufactured using Ar gas atomizer process. These alloy powders were consolidated using SPS process at different temperature under pressure 60 MPa in vacuum. Microstructures of the gas-atomized powders and sintered alloys were analyzed using scanning electron microscopy (SEM) with energy-dispersive X-ray spectrometer (EDS), and transmission electron microscopy (TEM). Hardness of the SPS sintered alloys was measured using micro Vickers hardness tester. The Al-Cr-Si bulks with high Cr and Si content were produced successfully using SPS sintering process without crack and obtained fully dense specimens close to nearly 100% T. D. (Theoretical Density). The maximum values of the hardness were 834 Hv for the sintered specimen of the gas atomized Al-30Cr-20Si alloy. Enhancement of hardness value was resulted from the formation of the multi-intermetallic compound with the hard and thermally stable phases and fine microstructure by the addition of high Cr and Si.