新型镍基粉末高温合金连续加热过程中γ′相溶解行为

Dissolution behavior ofγ′phase of novel nickel-based powder superalloy during continuous heating

本文通过SEM、XRD、EDS等实验表征方法,对一种新型镍基粉末高温合金在连续加热过程中γ′相的溶解行为进行系统研究。结果表明:随着温度以5℃/min缓慢升高,三次γ′相在1080℃时最先完全溶解,二次γ′相在1140℃时完全溶解,一次γ′相在升温至1160℃时仍有少量残留;γ′相面积分数从初始态的48.7%减小至1160℃时的0.3%;γ/γ′相错配度由1000℃时的0.264%减小至1120℃时的0.25%,而升温至1140℃时又增大至0.253%,升温至1160℃时再减小至0.248%。阐明了三类γ′析出相的溶解机制:大尺寸不规则一次γ′相通过γ/γ′相界面向内分裂成两个或多个具有平行界面的颗粒溶解;八角形二次γ′相通过分裂为八个细小颗粒溶解;小尺寸球状三次γ′相通过γ/γ′相界面处的元素扩散逐渐溶解。

In this paper,the dissolution behavior ofγ′phase of a novel P/M nickel-based superalloy during continuous heating process was systematically studied utilizing field emission scanning electron microscope(FESEM),X-ray diffraction(XRD),and energy dispersive spectrometer(EDS).The results show that,as the temperature increases with a speed of 5°C/min,the tertiaryγ′precipitates are dissolved completely at 1080℃;the secondaryγ′precipitates are dissolved entirely at 1140℃;and a small amount of residual primaryγ′precipitates are left at 1160℃.The area fraction ofγ′precipitates decreases from 48.7%for the initial HIPed FGH4113A alloy to 0.3%for the continuous heating one.The lattice misfit parameter ofγ/γ′phase firstly decreases from 0.264%at 1000℃to 0.25%at 1120℃,then increases to 0.253%at 1140℃,and at last decreases to 0.248%at 1160℃.The dissolution mechanism of three populations ofγ′precipitates is clarified as that,the complex-shaped primaryγ′precipitates split through theγ/γ′phase interface into two or more particles with parallel interfaces;the octocube secondaryγ′precipitates splits into eight fine particles through theγ/γ′phase interface;the nearly spherical tertiaryγ′precipitates are dissolved through the element diffusion at theγ/γ′phase interface.