剪切力对半固态Sn-Bi合金的组织演变与塑性的影响

Effect of shear force on microstructure evolution and plasticity of semi-solid Sn-Bi alloy

采用机械搅拌半固态铸造技术制备Sn-62Bi合金,通过XRD、EDS等测试方法探索了不同固相率下剪切力和作用时间对半固态Sn-Bi合金组织和塑性的影响。结果表明:在半固态温度145℃、搅拌速度为500 r/min和搅拌时间为15 min的工艺条件下,制备出分布均匀、尺寸约30μm块状铋初生相的半固态Sn-62Bi合金,拉伸试验下的伸长率为39.9%,与在180℃下的合金金属熔液直接水冷凝固而成的试样相比,其伸长率提高了283.3%。当搅拌温度为150℃时,随着搅拌时间的延长,块状初生相Bi相相互摩擦和碰撞破碎,初生相的尺寸减少,分布较均匀,所制备的半固态Sn-62Bi合金的伸长率得到改善。

The hypereutectic Sn-62Bi alloy was Obtained by semi-solid mechanical stirring casting technology. The influences of shear force and stirring time on the microstructure and plasticity of semi-solid alloy under different solid phase ratios were investigated. The results show that the semi-solid Sn-62Bi alloy with uniform distribution and fine quadrate primary Bi phase is obtained at agitating rate of 500 r/min, the temperature of 145 ℃ and the stirring time of 15 min. The size of quadrate primary Bi phase is about 30 pm. The elongation of semi-solid Sn-Bi alloy prepared is 39.9%, which is improved by 283.3%, compared to that of Sn-62Bi alloy prepared from the molten alloy at 180 ℃ and solidified in water. When the agitating temperature is 150℃, the friction and collision of quadrate primary Bi phase particles increase with increasing the stirring time, the probability of the friction and collision between quadrate primary Bi phase particle increases with increasing the stirring time, which leads to that the particles sizes become smaller and the particles distributions are uniform, and the elongation is improved.