时效对Ti-22Al-24Nb合金显微组织及力学性能影响

Effect of aging treatment on microstructure and mechanical properties of Ti-22Al-24Nb alloy

研究了经1000℃／2h／WC（水冷）固溶处理的Ti-22A1-24Nb合金在不同时效条件下的组织演变规律，且进行了不同时效时间下组织的力学性能测试。结果表明：时效时间对显微组织中相的含量和尺寸的变化影响较为明显。随时效时间增至24h时，部分晶粒发生了长大，且次生α2／O相长大明显，初生的α2相长大并等轴化。随时效温度的升高，晶粒尺寸变化不明显。经780℃／20h／AC（空冷）时效处理后，合金常温力学性能提升较小，抗拉和屈服强度分别提升至1022和950MPa，但塑性却大大降低至3％左右，随时效时问延长至24h，强度增加，塑性变化不大；合金高温力学性能为强度增加不明显，但塑性明显增加，其伸长率为20．27％，随时效时间延长至24h，合金的高温强度进一步增加，抗拉强度为1019MPa，屈服强度为977MPa，但高温塑性出现了下降。

The microstructure evolution of Ti-22A1-24Nb alloy which was treated at 1000 ℃/2 h/WC （ water cooling） solution treatment under different aging conditions was studied, and the mechanical property tests under different aging time conditions were carried out. The results indicate that aging time has obvious effect on the content and size of phase in microstructure. With the in- crease of aging time up to 24 h, parts of the grains begin to grow, and the secondary α2/O phase grows obviously, and the primary α2 phase begins to grow and to be equiaxial. With the increase of aging temperature, the change of grain size is not obvious. After the aging treatment of 780 ℃/20 h/AC （air cooling） , the mechanical properties of the alloy at room temperature show as follows： the improvement of alloy strength is small, the tensile strength increases to 1022 MPa and and yield strength increases to 950 MPa, but the plasticity decreases greatly to 3% ; with the the aging time increasing to 24 h, the strength of the alloy increases but the plas- ticity is almost unchanged. After the aging treatment of 780 ℃/20 h/AC （ air cooling） , the mechanical properties of the alloy at high temperature show as follows： the alloy strength increases rarely, but the plasticity increases obviously, the elongation is 20.27% ; with the aging time increasing to 24 h, the tensile strength increases to 1019 MPa and yield strength increases to 977 MPa, but the plasticity at high temperature decreases.