Inconel718高温合金Laves相及碳化物析出机理

doi:10.13251/j.issn.0254-6051.2024.03.032

摘要/Abstract

摘要： 为得到Inconel718高温合金Laves相及碳化物的析出规律,利用Thermal-Calc软件中的镍基数据库计算了平衡态下合金的相组成,采用光学显微镜、扫描电镜和场发射电子探针显微分析仪对合金进行了显微组织观察和能谱分析,并对析出相中的元素偏析状况进行了研究。最后利用高温激光共聚焦显微镜探究了合金的熔化与凝固规律。结果表明,平衡状态下Inconel718合金冷却过程中的相变顺序为液相、L+γ相、L+γ+MC相、L+γ+MC+δ相、γ+MC+δ+η相、γ+MC+δ+η+σ相、γ+MC+δ+η+M₂₃C₆相;合金中Ni、Cr和Fe元素表现为负偏析,以枝晶干分布为主,Nb元素表现为正偏析,以枝晶间分布为主;合金的固相线温度为1380 ℃,在凝固过程中,随着冷却速率的增加,合金开始凝固的温度逐渐降低,实现完全凝固所需的时间减少,液相分数随温度的升高也逐渐减小;此外根据凝固过程中析出相及组织变化,将整个凝固过程分为初始、稳定和最后凝固阶段;凝固结束后合金中二次枝晶间距与冷却速率的1/3次方成反比。

关键词: Inconel718高温合金, 析出相, 熔化和凝固, 二次枝晶间距, 冷却速率

Abstract: In order to obtain the precipitation law of Laves phase and carbides of Inconel718 superalloy, the phase composition of the alloy in equilibrium was calculated using the nickel-based database in Thermal-Calc software. The microstructure and energy spectrum of the alloy were observed by means of optical microscope, scanning electron microscope and field emission electron probe microanalyzer, and the element segregation in the precipitated phase was explained. Finally, the melting and solidification process of the Inconel718 nickel-base superalloy was studied by using high-temperature laser confocal microscope (HT-CLSM). The results show that the phase transformation sequence of the Inconel 718 alloy during cooling is liquid phase, L+γ phase, L+γ+MC phase, L+γ+MC+δ phase, γ+MC+δ+η phase, γ+MC+δ+η+σ phase, γ+MC+δ+η+M₂₃C₆ phase; Ni, Cr and Fe elements in the alloy are mainly distributed in the dendrite trunk, showing negative segregation, while Nb element is mainly distributed in the interdendritic, showing positive segregation. The solidus temperature of the alloy is 1380 ℃. During the solidification process, with the increase of cooling rate, the temperature at which the alloy begins to solidify gradually decreases, the time required to achieve complete solidification decreases, and the liquid fraction also decreases with the increase of temperature. In addition, the whole solidification process is divided into initial, stable and final solidification stages according to the precipitation phase and microstructure changes during the solidification process. At the same time, the secondary dendrite spacing in the alloy is proportional to the third power of the cooling rate after solidification.

Key words: Inconel718 superalloy, precipitated phase, melting and solidification, secondary dendrite spacing, cooling rate

中图分类号:

TG132.3

郭续龙, 周扬, 陈琦. Inconel718高温合金Laves相及碳化物析出机理[J]. 金属热处理, 2024, 49(3): 190-197.

Guo Xulong, Zhou Yang, Chen Qi. Laves phase and carbide precipitation mechanism of Inconel718 superalloy[J]. Heat Treatment of Metals, 2024, 49(3): 190-197.

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