Fabrication of In-situ Formed Al₃Zr Reinforced Al Sintered Composites and Their Tribological Behavior

Abstract

Powder metallurgy (PM) Al₃Zr reinforced aluminum (Al) composites were fabricated by in-situ reaction during spark plasma sintering (SPS) using the pre-mixed Al and zirconium hydride (ZrH₂) powders. The diffusion behavior of Al and zirconium (Zr) elements in Al matrix were studied. It was clarified that ZrH₂ decomposed at around 773 K and dissolved Zr elements reacted with Al matrix to form Al₃Zr layers around ZrH₂ particle. Al₃Zr compounds grew toward the center of ZrH₂ particle due to a faster diffusion rate of Al compared to Zr element. The tribological behavior of the composite material was investigated by using pin-on-disk wear test under lubricated condition. Friction coefficient and wear volume of Al-Al₃Zr composite were much lower than those of pure Al. SEM observation and SEM-EDS analysis on wear track of pin and disk specimens were investigated. The sliding surface of SUS304 stainless steel counterpart after wear test showed very slight damages and no seizure phenomenon with the pin specimen. It is concluded that PM Al-Al₃Zr composite had a good tribological property and wear resistance due to hard Al₃Zr particles dispersed in Al matrix preferentially contacting the counterpart material to prevent the soft Al matrix in direct contact with SUS steel surface.