激光沉积TC4/TC11梯度材料组织与疲劳性能研究

Microstructure and fatigue properties of TC4/TC11 gradient materials by laser deposition

摘要:

为了研究激光沉积TC4/TC11钛合金梯度材料的组织与疲劳性能,采用激光沉积制造技术制备两种不同过渡方式的TC4/TC11复合材料。观察不同过渡方式复合材料的显微组织,测试两种复合材料分别在550Mpa和800Mpa下的疲劳性能,并对疲劳断口进行分析。结果表明,相比直接过渡的复合材料,具有3层过渡层梯度材料的显微组织过渡界面不明显,过渡区组织结合紧密；具有3层过渡层的梯度材料在两种应力下的疲劳寿命均比直接过渡的高,低应力下相对提高了129.3%,高应力下相对提高了81.8%；直接过渡复合材料在裂纹扩展时沿着α片层集束开裂,滑移面较大,疲劳寿命较低；具有3层过渡层的梯度材料,裂纹扩展沿着单个α片层滑移开裂,滑移面小,裂纹扩展路径比较曲折,疲劳寿命高。

Abstract:

In order to study the microstructure and fatigue properties of laser deposited TC4/TC11 gradient materials, directly transited and gradiently transited TC4/TC11 composite materials were prepared by laser deposition manufacturing technology. The microstructures of composite materials by different transition were observed, the fatigue properties of these two composite materials under stresses of 550 MPa and 800 MPa were tested, and fatigue fractures were analyzed. The results show that the interface of the microstructure of the gradient material with 3 transition layers is not obvious, and microstructures of TC4 and TC11 are integrated more tightly in the transition zone than that of the directly transition composite materials. The fatigue life of the gradient material with 3 transition layers under either stress is higher than that of the direct transition, which is relatively increased by 129.3% under low stress and 81.8% under high stress. The direct transition composite material cracks along the bunch of α-sheet during crack propagation, with a large sliding surface and a low fatigue life. The cracks of gradient material with 3 transition layers grow along a single α-sheet, the slip plane is small, and the crack propagation path is more tortuous, which improves the fatigue life.