This study investigates the effect of Strontium (Sr) grain modifier addition on Al-9Si alloy and B₄C reinforced composite fabricated by two step gravity casting technique. The optimum level of Sr was identified as 0.08 wt.% for complete modification. The modified cast components were thermally treated by T6 temper to enhance the tribo-mechanical properties. Metallographic observation revealed the transformation of acicular Si grains to fine fibrous in as-cast condition, which later transformed to spheroidised eutectic Si after heat treatment. The combined effect of grain modification by Sr and the influence of spheroidised eutectic Si enhanced the mechanical properties. Heat treated modified composite exhibited superior tribological properties when compared to other components under varying applied normal loads and sliding distances. Worn mechanism of heat treated modified composite was observed to be minor delamination wear regime at high load (55 N) and sliding distance (1500 m).

这项研究调查了锶（Sr）晶粒改性剂的添加对Al-9Si合金和B _4的影响通过两步重力铸造技术制备的C增强复合材料。为了完全改性，确定最佳的Sr含量为0.08重量％。改性铸件通过T6回火进行热处理，以增强摩擦机械性能。金相观察表明，在铸态条件下，针状硅晶粒转变为细纤维，热处理后又转变为球状共晶硅。Sr对晶粒的改性作用与球化的共晶Si的影响共同提高了机械性能。与其他组件相比，经热处理的改性复合材料在变化的法向载荷和滑动距离下表现出优异的摩擦学性能。