烧结与冷镦过程中铝硅共晶合金显微结构与密度的演变

采用烧结及后续的镦粗工艺制备了铝硅共晶合金块体材料,研究了烧结温度对烧结体显微结构、抗压强度及相对密度的影响。结果表明：烧结温度显著影响烧结体的显微结构和抗压强度,以临近铝硅共晶合金液相线的温度烧结时,发生了局部熔化,产生的熔融液体破坏了颗粒表面的氧化膜,颗粒之间相互黏结,形成了烧结骨架。以优化的555℃烧结,Si颗粒呈球状,抗压强度达到最佳,但相对密度未发生变化。在后续的冷镦过程中,烧结骨架及粉末颗粒均产生变形,孔隙减小,颗粒呈扁平状,相对密度达到了98%。

Evolution of AI-Si Eutectic Alloy Microstructure and Density during Sintering and Cold Upsetting

The Al-Si eutectic alloy blocks are prepared by sintering and post upsetting. The effects of sinter temperature on micro- structure, compressive strength, and relative density of sintered billets are investigated. It is shown that the sintering temperature influ- ences sensitively the microstructure and compressive strength of sintered billets. Sintered at the temperature near to liquidus boundary of Al-Si eutectic alloy, some local melting occurs. The melted liquid disrupts the oxide film covering the particles. Particles bond with each other to form skeleton frame. The optimal sintering temperature is 555 ~C, at which the Si particle is spherical-like and the com- pressive strength is better, but the relative density almost has no change. During post upsetting, the skeleton frame and the particles are deformed. The pore space reduces and the particles become into flat. The relative density reaches to 98%.