Effect of sintering temperature and postpone hot cross rolling process on physical, mechanical, and microstructural properties of Al/B۴C composite fabricated by hot pressing process

The aim of this study is investigation of the effect of sintering temperature and hot cross rolling process on physical, mechanical and microstructural properties of Al-۳۰ wt. % (B۴C) composite fabricated by hot pressing process. Powders of Aluminum with ۲۰ μm and B۴C with ۴۵ μm particle size were milled by planetary mill machine for ۴ h with ۲۰۰ rpm. Then mixed powder was sintered by hot pressing machine at ۵۵۰, ۶۰۰, and ۶۵۰ °C for ۱ h under ۵۰ Mpa in a vacuum. Then samples were preheated at ۵۰۰ °C for ۲۰ min and hot cross rolled in ۸ passes (۲۵ % reduction). For characterization of the samples, density of the samples by Archimedes method, microhardness, XRD, and FESEM analysis were performed. The results showed the density and hardness of hot pressed samples were increased from ۲.۲۹ to ۲.۵۱ g/cm۳, and ۹۰.۵۶ to ۱۲۷.۳۳ Vickers, respectively. Also, after hot cross rolling, the density and hardness of the samples were increased from ۲.۳۵ to ۲.۶۴ g/cm۳, and ۹۰.۵۶ to ۱۲۷.۳۳ Vickers, respectively. X ray patterns showed inter phases such as AlB۳۱ form during hot pressing process. Also, performing of hot cross rolling process can lead to decrease the size of B۴C particles and uniform distribution in Aluminum matrix. The best sintering temperature at ۶۵۰ OC and performing ۲۵ % hot cross rolling process lead to have a composite with the highest density and lowest porosity and water absorption.