固溶处理参数对一种单晶高温合金微观偏析的影响

摘要

A Ni-base single-crystal superalloy containing 4wt.%Re was directionally solidified under liquid metal cooling (LMC), followed by stepwise solution treatments. Under high thermal gradient, the dendrite structures are greatly refined with increasing withdrawal rates. After the stepwise solution heat treatments, the residual segregation of alloying elements such as Ta, Re and W etc., reduces with the refined structure, which can be attributed to the reduced characteristic diffusion distance, hi addition, as the increase of solution-treated temperatures, the residual segregation of refractory elements can be reduced.%采用液态金属冷却法,对一种含4wt.％Re的单晶高温合金进行高温度梯度定向凝固试验,并通过改变固溶处理温度和时间对其进行多步固溶处理.结果表明:高温度梯度定向凝固可以显著地细化枝晶,降低Re、W、Ta等难熔元素的枝晶偏析；溶质的特征扩散距离也随枝晶的细化而减小,经多步固溶处理后,合金各组元的残余偏析程度显著降低；此外,适当提高固溶热处理温度,可以起到减轻枝晶偏析的作用.