Effect of pre-annealing on microstructure and compactibility of gas-atomized Al-Si alloy powders

预退火对气雾化Al-Si合金粉末显微组织和压制性能的影响（英文）

Effect of pre-annealing treatment temperature on compactibility of gas-atomized Al-27%Si alloy powders was investigated. Microstructure and hardness of the annealed powders were characterized. Pre-annealing results in decreasing Al matrix hardness, dissolving of needle-like eutectic Si phase, precipitation and growth of supersaturated Si atoms, and spheroidisation of primary Si phase. Compactibility of the alloy powders is gradually improved with increasing the annealing temperature to 400 ℃. However, it decreases when the temperature is above 400 ℃ owing to the existence of Si-Si phase clusters and the densely distributed Si particles. A maximum relative density of 96.1% is obtained after annealing at 400 ℃ for 4 h. In addition, the deviation of compactibility among the pre-annealed powders reaches a maximum at a pressure of 175 MPa. Therefore, a proper pre-annealing treatment can significantly enhance the cold compactibility of gas-atomized Al-Si alloy powders.

研究预退火温度对气雾化Al-27%Si合金粉末压制性能的影响,并分析退火粉末的显微组织和硬度。预退火不仅降低Al基体硬度,而且导致针状共晶Si相熔解、过饱和固溶Si原子析出和长大以及初晶Si相球化。合金粉末的压制性能随着退火温度升高至400°C而逐渐提高;但是,由于出现Si-Si相缠结和密集分布的Si颗粒,粉末的压制性能在退火温度高于400°C时反而有所下降。粉末在400°C退火4 h后,其相对密度最大达到96.1%。另外,预退火合金粉末压制性能的差异在压制压力为175 MPa时达到最大。因此,通过合适的预退火处理可以大幅提高气雾化Al-Si合金粉末的室温压制性能。