Modification of hypereutectic Al-Si alloy surface layer structure by Nb alloying under high temperature plasma impact

Abstract

Phase composition, microstructure, and microhardness of the hypereutectic Al-Si alloy (22.3 wt.% of Si) surface layer alloyed with Nb atoms under compression plasma flows treatment (energy absorbed by the surface layer 25–35 J/cm2 per pulse) were investigated. X-ray diffraction analysis and scanning electron microscopy were used for surface layer characterization. The findings showed that plasma impact on the Nb/Al-Si system led to an alloyed layer formation in Al-Si with the thickness of 10–45 μm that was dependent on the treatment regimes. Alloyed layer contained (Al,Si)3Nb intermetallic compound. Alloying of Al-Si with niobium atoms led to its hardening. Annealing of alloyed samples at 170°C in air also resulted in microhardness growth.