脉冲电流作用下LY12铝合金凝固组织变化

The Variation of Solidification Structures of LY12 Al Alloy Solidified under Pulsed Current

在LY12铝合金凝固过程中施加脉冲电流,研究脉冲电流的不同放电电压对宏观凝固组织、溶质元素晶内含量及宏观偏析的影响。脉冲电流的放电工艺为:固定脉冲电容器的电容为80μF,放电电压在3~7kV之间变化。通过试验发现,与未施加脉冲电流的试样相比,不同放电电压的脉冲电流作用可以使试样的宏观组织得到不同程度的细化,细化效果并非总是随放电电压的增加而越来越明显,而是存在一个最佳电压值,当放电电压为5kV时,细化效果最显著。同时,经过脉冲电流处理后,LY12铝合金中Cu元素的晶内含量得到显著提高,Cu元素的宏观偏析得到有效抑制,偏析率明显减小。初步阐明了脉冲电流的作用机制。

A pulsed current was applied on the solidification process of LY12 Al alloy.The effect of discharging voltage of pulsed current on the macrostructures,solute content inside the grain and macro-segregation were studied.The discharge process was as follows:the capacitorhad 80 μF capacitance and the dischargevoltagevaried from 3kV to 7kV.It was found through experiments that,comparing with the sample solidified in the absence of pulsed current,the macrostructures of samples solidified under pulsed current of different discharging voltagewere refined at different degree.The refinement was not always more obviousalong with the increasingof the discharge voltage and there is an optimal voltage.The refinement was most remarkablewhen the discharging voltagewas 5kV.Meanwhile,after treated with pulsed current,the Cu content inside the grain of LY12 Al alloy obviously increased.The macro-segregation ofCu can be restrained effectively and the segregation ratiowas reduced evidently.The mechanism of pulsed currentwas discussed preliminarily.