Al-20Si合金梯度材料的组织与性能

Structure and Properties of Al-20Si Alloy Functionally Gradient Materials

用离心技术制得了过共晶Al 2 0Si合金梯度材料 ,离心机转速 14 0 0r/min ,金属模具预热温度 4 5 0℃ ,浇注温度 80 0℃。研究表明 ,在离心力场中初晶Si向试样内侧移动。Al 2 0Si合金梯度材料最内层初晶硅含量最多、尺寸也最大 ,由内向外 ,初晶硅的体积分数及尺寸均逐渐减小 ,呈梯度变化。材料内层硬度较高、耐磨性较好 ,由内向外硬度逐渐减小、耐磨性变差 ,呈梯度变化。

Hypereutectic Al 20Si alloy functionally gradient materials (FGM) were made by centrifugal casting method. The rotation speed of the centrifugal machine was 1 400 r/min. The metal mold was preheated at 450 ℃. The melted metal was poured at 800 ℃. The gradient distribution law of structure, hardness and wear resistance of the FGM were studied by means of optical microscope and SEM, HV 5 model light load Vickers, and ML 100 model pin disk abrasive wear testing machine. The results showed that the primary crystal Si particles segregated to the inside of specimens in centrifugal field because the density of the primary crystal Si particles was smaller than that of Al alloy melt. The content and size of the primary crystal Si particles decreased gradually from the inside to the outside of the specimen, and changed in gradient. The hardness and wear resistance of Al 20Si alloy FGM reduced gradually from the inside to the outside of the specimen, changed in gradient.