Microstructure and Wear Properties of T6 Heat Treated Semisolid A356-TiB_2 composite

摘要

The aim of this study is to investigate the microstructure and wear properties of T6 heat treated semisolid A356 composite containing 1.5 wt.% and 2.63 wt.% TiB_2. The semisolid A356-TiB_2 composite was prepared using a cooling slope casting technique. The sample, then was solution treated at different temperatures (500°C, 520°C and 540°C) for 5 hours soaking time. Then, age hardening was conducted at different temperatures (120°C, 150°C and 180°C) for 8 hours. Semisolid A356 composite was characterized for microstructure, microhardness and wear properties. Microstructure of semisolid A356 composite was refined with a higher amount of TiB_2. High solution treated temperature (540°C) resulted in the finer size of Si particles in the semisolid A356 alloy. Microhardness of solution treated semisolid A356 alloy achieved higher hardness at 540°C with a hardness value of 75.16 HV. Solution treated of semisolid A356 composite containing 1.5 wt.% TiB_2 has the smallest Si particles and the highest hardness of 119.7 HV. Among the samples, A356-1.5 wt.% composite after aging at 180°C showed the highest hardness (129.7 HV). Wear resistance of semisolid A356 alloys was improved by the addition of TiB_2. Wear surface morphology revealed that the adhesive and abrasive wear mechanism present.