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通过研究C微合金化对层片组织Ti Al合金800℃/300 MPa蠕变变形行为、组织分解以及应变硬化的影响,以解释C微合金化对层片组织高应力蠕变变形均匀性的影响。结果表明:在Ti-47.5Al-2.5V-1.0Cr-0.2Zr合金中添加0.1%C(原子分数),显著改善了该合金的抗蠕变性能,其中,合金800℃/300 MPa蠕变变形进入第三阶段的时间增加了2.5倍,相同时间蠕变应变量降低了72%,同时使其最小蠕变速率降低了近一个数量级。添加C显著改善了该合金较高应力条件下抗蠕变性能及蠕变变形均匀性。其原因是C微合金化在合金层片团界和层片界面引入碳化物析出相,层片组织抵抗剪切变形的作用,从而延缓了蠕变变形过程中再结晶和层片组织分解的发生;同时,初始组织中的碳化物改善了合金的应变硬化能力,蠕变过程中在中断的γ层片台阶处析出的碳化物起到动态硬化效果,也是添加C改善Ti Al合金层片组织较高应力蠕变变形均匀性的原因。
The effect of C microalloying on the creep deformation behavior, microstructure and strain hardening of TiAl alloy at 800 ℃ / 300 MPa was studied to explain the influence of C microalloying on the high-stress creep deformation uniformity of the lamellar structure . The results show that the addition of 0.1% C (atom fraction) to Ti-47.5Al-2.5V-1.0Cr-0.2Zr alloy significantly improves the creep resistance of the alloy. The creep deformation of the alloy at 800 ℃ / 300 MPa When entering the third stage, the time increased by 2.5 times and the creep strain decreased by 72% at the same time, meanwhile the minimum creep rate was reduced by nearly one order of magnitude. The addition of C significantly improves the creep resistance and creep deformation uniformity of the alloy under higher stress conditions. The reason for this is that C microalloying introduces a carbide precipitation phase at the interface of the alloy layer and the interface of the layer, and the layer structure resists shear deformation, thereby delaying the occurrence of recrystallization and delamination of the layer structure during creep deformation ; At the same time, the carbides in the initial microstructure improve the strain hardening ability of the alloy. The carbides precipitated at the discontinuity of the gamma ply during the creep process have a dynamic hardening effect, and also the effect of adding C to improve the microstructure of the TiAl alloy ply Causes of high stress creep deformation uniformity.