激光表面重熔过共晶铝硅合金的组织与性能

利用CO2连续横流激光器对过共晶铝硅合金活塞表面进行激光重熔，研究了重熔后过共晶铝硅合金的组织结构、硬度和耐磨性能相对于基体的变化。结果表明，重熔后的过共晶铝硅合金的显微组织结构可分为重熔区、过渡区和基体3个对比明显的区域。重熔区与基体相比，组织明显细化。初晶Si形状由粗大的多角形或方形变为棱角不明显的胞状，共晶Si由针条状变为细小颗粒状。表面重熔区的硬度（HV）提高了近40，耐磨性能明显高于基体材料。同时，分析了重熔区组织细化的原因。

Microstructure and Properties of Hypereutectic Al-Si Alloy by Laser Surface Remelting

The change of structure, hardness and wear resistant of remelted hypereutectic Al-Si alloy has been observed by remelting surface of the alloy piston with CO_2 continuous transverse-flow laser. The results show that the microstructure of remelted alloy consists of remelting zone, transition zone and matrix zone. Compared with that in matrix zone, the grain size in transition zone is obviously refined, where primary Si is converted from bulky polygonal or square into cell, and eutectic Si is transformed from needle-like strip into fine particle. The hardness of surface remelting zone is increased by 40 Hv, superior to matrix in wear resistant. The refinement mechanism of the remelting zone is analyzed.