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本工作系统地研究长期高温时效对高铬含量的Ni-基耐热腐蚀合金组织稳定性的影响。发现高铬含量使TiC相变得不稳定,950℃以上有明显溶解,通过相界反应转变成Cr_(23)C_6而溶入基体中。850℃长期时效不出现η和TCP相,易发生MC蜕化反应和Υ′粗大化,性能稳定,塑性逐渐提高。合金相组分与热处理制度无关。断口分析确定合金长期时效后塑性提高的原因是晶界上的大块脆性TiC转变成细小的、具有嵌镶结构的,包有Υ′膜的Cr_(23)C_6,提高了塑性。最后计算了合金基体的强度和长期时效后Υ′相对强度的贡献,结果与实验相符。
This work systematically studied the effect of long-term high temperature aging on the microstructure stability of high chromium content Ni-based heat-resistant corrosion alloy. It was found that the high chromium content makes the TiC phase unstable, which is obviously dissolved above 950 ℃ and transformed into Cr_ (23) C_6 into the matrix through the phase boundary reaction. Long-term aging at 850 ℃ does not appear η and TCP phase, easy to MC degeneration and Y ’coarsening, stable performance, plastic gradually increased. Alloy phase composition and heat treatment system has nothing to do. Fracture analysis shows that the plasticity of the alloy after long-term aging is due to the transformation of the large brittle TiC on the grain boundary into a small, inlayed Cr_ (23) C_6 coating with Y ’film, which improves the ductility. Finally, the contribution of the strength of the alloy matrix and the relative intensity of the Y ’after long-term aging is calculated. The results are consistent with the experimental results.