Nb element segregation behavior and homogenization law of GH2909 superalloy

doi:10.13251/j.issn.0254-6051.2025.02.033

Abstract

Abstract: Theoretical homogenization process of GH2909 alloy was calculated via JMatPro and homogenization experimental verification was conducted for the as-cast alloy at 1130 ℃ to 1190 ℃. Microstructure, element segregation and dissolution of Laves phase of the as-cast and homogenized GH2909 alloy were characterized by means of metallurgical microscope, scanning electron microscope and electronic probe. After heat treatment at 845 ℃ for 4 h and then air cooling for the homogenized GH2909 alloy, the distribution of needle-like η phase was observed, in order to evaluate homogenization effect of the GH2909 alloy. The results show that a mass of low melting point Laves phase exists in the as-cast GH2909 alloy and Nb element is the most important segregation element. Laves phase dissolves completely in the GH2909 alloy after 1150 ℃×7 h or 1130 ℃×10 h homogenization treatment. After complete Laves phase dissolution, 1190 ℃×35 h homogenization treatment decreases segregation coefficient to 1.046 and residual segregation coefficient to 0.059 of Nb element. After heat treatment at 845 ℃ for 4 h and air cooling for homogenized specimens, Nb-rich needle-like η phase precipitates along grain boundary and in grain with uniform diffusion of Nb element. Combining segregation coefficient with η phase precipitation behavior, 1150 ℃×7 h+1190 ℃×35 h homogenization treatment can realize complete homogenization of the GH2909 alloy.

Key words: GH2909 superalloy, homogenization, Laves phase, Nb, element segregation

CLC Number:

TG156.21

Qi Huilin, Guo Xulong, Chen Qi, Zhou Yang. Nb element segregation behavior and homogenization law of GH2909 superalloy[J]. Heat Treatment of Metals, 2025, 50(2): 212-217.

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