GH4169合金均匀化过程中相变动态原位研究

Dynamic In-situ Study on Phase Transition of GH4169 Superalloy During Homogenization Process

为揭示GH4169合金在均匀化处理过程中成分和组织的演变规律,利用高温金相显微镜实时原位观察热处理过程中合金的显微组织,定量分析了冷却后合金中Laves相的粒度分布,用电子探针EPMA探讨了合金中Nb元素在热处理前后的分布规律。结果表明,GH4169合金升温到1151℃时,邻近Laves相周围区域开始初熔。1180℃热处理后GH4169合金中Laves相颗粒数增加,但Laves相最大颗粒尺寸显著减小,小颗粒Laves相比例略有增加。在1180℃保温时,GH4169合金中已有液相存在,但NbC未溶解。热处理后合金中原枝晶间黑色区域的Nb元素偏析仍存在,但Nb元素在枝晶轴γ相中分布更加均匀。

In order to reveal the evolution of composition and microstructure of GH4169 alloy during the homogenization treatment, the alloy microstructures during heat treatment were in-situ observed by high temperature metallographic microscope. The particle size distribution of Laves phase in the alloy after cooling was analyzed by quantitative metallographic analysis. The distribution characteristics of Nb element in alloy before and after heat treatment were analyzed by EPMA. The results show that when the heating temperature of GH4169 alloy rises to 1151 ℃, the initial melting happens around the Laves phase. The particle number of Laves phase in GH4169 alloy increases after heat treatment at 1180 ℃, the particle size of maximum Laves phase decreases significantly, and the proportion of small Laves phase in alloy increases slightly. At 1180 ℃, there is a certain amount of liquid phase existing in GH4169 alloy, but the NbC phase undissolves. After heat treatment, the segregation of Nb element in the black area between the primary dendrites still exists, but the distribution of Nb element in the γ phase dendrite becomes more uniform.