过冷Ni-1at%Fe合金晶粒细化及再结晶机理分析

通过熔融玻璃净化与循环过热相结合的方法研究了过冷Ni-1at%Fe合金的微观组织演化及再结晶。通过再辉后快淬和空冷实验对比,证明大过冷下的细化组织是再结晶的产物。结合无量纲过热度的计算,系统考察了合金凝固组织随过冷度的演化规律。研究发现合金的凝固组织在所获得的过冷度范围内发生了两次晶粒细化,第一次细化归因于枝晶的熟化和重熔导致的高度发达树枝晶碎断,第二次细化归因于应力积累导致的再结晶。

Research on Grain Refinement and Recrystallization Mechanism of Undercooled Ni-1at%Fe Alloy

The microstructure evolution and the recrystallization of undercooled Ni-1at%Fe alloy were investigated by employing the glass fluxing technique in combination with cyclical superheating. The experiments of rapid quenching and naturally cooling on Ni-1at%Fe alloy after recalescence were conducted. It is proved that the fine structure is the product of recrystallization under high undercooling. The evolution of microstructure was systematically investigated by applying the calculation of dimensionless superheating. Two grain refinements were detected. The first grain refinement occurs owing to the dendrite break-up or ripening induced by remelting. The second grain refinement occurs due to the recrystallization induced by stress cumulation.