Segregation of Phosphorus and Precipitation of MNP-Type Phosphide at the Grain Boundary of IN706 Superalloy

• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2017,（2）
• 页码范围: 187-191
• 页数: 5页
• 语种: 英文

摘要

The effect of phosphorus content and heat treatment on the segregation of phosphorus and precipitation of phosphide at the grain boundary of IN706 alloy has been investigated.The phosphide had a stoichiometry of MNP (M =Nb,Ti and N =Ni,Fe,Cr) and an orthorhombic crystal structure.The solubility of phosphorus in the grain matrix of IN706 alloy was determined to be between 0.008％ and 0.013％.When soaked at 980 ℃ for 5 min,the phosphide was noticeably precipitated at grain boundaries with the grain size unchanged.When soaked at 980 ℃ for 3 h,the grains grew significantly,but the phosphide stayed at original grain boundaries which outlined the grain shape before soaking.Soaking at 1060 ℃for 2 h fully dissolved the pre-existing phosphide but phosphorus atoms were not distributed uniformly in the grain matrix.When the holding time at 1060 ℃ was extended to 10 h,the phosphorus atoms were distributed uniformly in the grain matrix by sufficient diffusion,and the phosphide could only be formed at grain boundaries during the 980 ℃ soaking.The precipitation of phosphide mainly relied on the phosphorus segregation which was built up by diffusion.