脉冲磁场下制备半固态铝铜合金坯料的研究

Preparation of Semi-solid Al-4.5Cu Alloys under Pulsed Magnetic Field

采用脉冲磁场技术制备了半固态Al-4.5Cu合金坯料,考察了冷却速度和脉冲频率对半固态坯料初生α-Al相形貌和尺寸的影响。结果表明,利用脉冲磁场处理可以制备出初生α-Al相为细小的近球状颗粒的半固态Al-4.5Cu合金坯料。初生α-Al相平均晶粒尺寸和平均形状系数分别随着冷却速度的减小和脉冲频率的增加而相应的减小和增加。但当冷却速度减小到20℃/min,脉冲频率增大到10Hz时,半固态组织有所粗化。当冷却速度为40℃/min,脉冲频率为6Hz时,半固态Al-4.5Cu合金坯料初生α-Al相平均晶粒尺寸最小,形貌最为圆整,适合于半固态成形。

Semi-solid Al-4.5Cu alloy billets were prepared by pulsed magnetic field technique,and the effects of cooling rate and pulsed frequency on solidified morphology and size of primary Al phase in semi-solid Al-4.5Cu alloy were observed.The experimental results show that semi-solid Al-4.5Cu alloy with near-spherical structure can be obtained by PMF treatment.The average size and shape coefficient of primary α-Al particles are decreased with decreasing in cooling rate and they are increased with increasing in pulsed frequency.However,with the cooling rate lower than 20 ℃/min and/or the pulsed frequency more than 10 Hz,the morphology of primary Al phase is coarsened.Primary α-Al particles with average diameter of about 96 μm and average shape factor of 0.58 in the semi-solid Al-4.5Cu alloy can be observed with cooling rate of 40 ℃/min and the pulsed frequency of 6 Hz,which is suitable for thixoforming.