Effects of strontium and heat treatment on the wear-corrosion property of Al–7Si–0.3Mg alloy

Al–Si alloy often exposed to unfavorable environment such as rain or seawater when they were utilized. The synergistic attack such as wear and corrosion can result in a higher rate of material removal. In the Al–7Si–0.3Mg (A356) alloy, the properties were influenced by the characteristic of eutectic Si particles as well as by the precipitate phase that occurs upon heat treatment. Microstructural changes caused by Sr modifier and subsequent heat treatment as well as the corresponding changes in wear-corrosion property of A356 alloy were studied. The results showed that the addition of Sr modifier changed the morphology of eutectic Si particles and further improved the wear and wear-corrosion properties. Compared to unmodified A356 alloy, the corrosion resistance decreased with addition of Sr. The deterioration in corrosion property triggered the reduction in improvement of wear-corrosion rate when the applied potential increased. The heat treatment of A356 alloy spheroidized and coarsened eutectic Si particles after the solution treatment, strengthened α-Al matrix after the aging treatment. The enhanced microstructure reduced the wear rate and improved the corrosion susceptibility of modified A356 alloy, which further enhanced the wear-corrosion resistance.