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通过深过冷凝固实验对Co-Ru包晶合金中不同相的析出及演化行为进行了研究。采用熔融玻璃净化与循环过热相结合的方法对该合金的深过冷实验获得了217 K(0.12 T L)的最大过冷度。结合经典形核理论的计算结果,在全过冷度范围内ξ相始终作为先析相优先从熔体中析出。当过冷度(ΔT)小于临界过冷度(ΔT*≈180 K)时,合金凝固组织表现为典型的包晶组织,此时包晶相的析出依赖于ξ相的形态改变;当ΔT>ΔT*时,虽然ξ相仍为先析相,但是包晶相α的析出不再依赖于ξ相,而是直接从过冷熔体中析出并与ξ相竞争长大。随着过冷度的增大,包晶相的相对含量先增加后减少最后再次增加。
The precipitation and evolution of different phases in Co-Ru peritectic alloys were investigated by deep overcooling solidification experiments. The maximum undercooling of 217 K (0.12 T L) was obtained from the deep overcooling experiments of the alloy by the combination of the purification of molten glass and overheating. According to the calculation results of the classical nucleation theory, the ξ phase is always preferentially precipitated from the melt in the range of total undercooling. When the undercooling (ΔT) is less than the critical undercooling (ΔT * ≈180 K), the solidified microstructure of the alloy shows the typical peritectic structure. At this time, the precipitation of the peritectic phase depends on the morphological change of ξ phase. When ΔT> ΔT *, although the ξ phase is still the first phase, the precipitation of the peritectic phase α no longer depends on the ξ phase, but precipitates directly from the supercooled melt and competes with ξ to grow up. With the increase of undercooling, the relative content of peritectic phase increases first and then decreases and finally increases again.