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采用双步机械球磨和放电等离子烧结(SPS)相结合的方法制备 Ti-45Al-2Cr-2Nb-1B-0.5Ta(at%)和 Ti-45Al-2Cr-2Nb-1B-0.5Ta-0.225Y(at%)2 种 TiAl 基合金(简称 TA 合金和 TAY 合金),并研究稀土元素 Y 对 TiAl 基合金显微组织和力学性能的影响。结果表明,通过双步机械球磨后的粉末形状比较规则,颗粒尺寸范围在 20~40 μm之间。经过 SPS 烧结的 TiAl 基合金块体主要由 TiAl相和 Ti3Al 相组成,还有少量的 Ti2Al 相和 TiB2相。SPS 烧结的 TA 合金块体试样等轴晶粒的尺寸在 100~400 nm 之间,合金的室温压缩强度为 2614 MPa,压缩率为 20.57%;而对于加入了稀土元素 Y 的 TAY 合金而言,等轴晶粒尺寸明显减小,合金的室温压缩强度为 2677 MPa,压缩率为 22.91%,跟 TA 合金相比力学性能有所改善。显微硬度的测试结果表明,SPS 烧结的 TA 合金的显微硬度要明显高于 TAY 合金。通过对压缩断口进行观察发现,SPS 烧结的 2 种 TiAl 基合金均为沿晶断裂。
Ti-45Al-2Cr-2Nb-1B-0.5Ta (at%) and Ti-45Al-2Cr-2Nb-1B-0.5Ta-0.225Y (at%) were prepared by a combination of two-step mechanical ball milling and spark plasma sintering (SPS) at%) two kinds of TiAl-based alloys (referred to as TA alloy and TAY alloy), and the effect of rare earth element Y on the microstructure and mechanical properties of TiAl-based alloys. The results show that the grain size ranged from 20 μm to 40 μm with the rule of powder shape after two-step mechanical ball milling. After sintering SPS TiAl-based alloy block mainly composed of TiAl phase and Ti3Al phase, there are a small amount of Ti2Al phase and TiB2 phase. The size of equiaxed grains of the SPS sintered TA alloy block specimen is between 100 and 400 nm, the room temperature compressive strength of the alloy is 2614 MPa and the compressibility is 20.57%. For the TAY alloy with rare earth element Y added , The equiaxed grain size is obviously reduced. The compressive strength at room temperature of the alloy is 2677 MPa and the compressibility is 22.91%. Compared with the TA alloy, the mechanical properties are improved. Microhardness test results show that, SPS sintered TA alloy microhardness is significantly higher than the TAY alloy. Through the observation of the compression fracture, found that two kinds of SPS sintered TiAl-based alloys are intergranular fracture.