反应热压(Al2O3+TiB2+Al3Ti)/Al复合材料的低周疲劳行为

LOW CYCLE FATIGUE OF (Al2O3+TiB2+Al3Ti)/Al COMPOSITES FABRICATED BY REACTIVE HOT PRESSING

  • 摘要: 采用反应热压法以Al、B2O3、TiO2粉和Al、B、TiO2粉为原料制备了两种(Al2O3+TiB2+Al3Ti)/Al复合材料。后一种原料粉制备的复合材料从基体中析出了细小的Al3Ti相。研究了应变控制原位生成复合材料的室温低周疲劳行为。结果表明,在应变幅较小时(ε</em>t≤0.3%),不含Al3Ti析出相的材料表现为循环稳定;而在应变幅较大时(ε</em>t≥0.4%), 则表现为第一周的循环硬化和随后的循环软化。在所采用的应变幅下,含Al3Ti析出相的材料均表现为循环稳定。疲劳裂纹萌生部位为Al3Ti相断裂、Al3Ti相与基体的界面开裂和基体中微裂纹。疲劳裂纹穿过基体,绕过Al2O3、TiB2质点扩展。两种复合材料的疲劳寿命均符合Coffin-Manson公式。

     

    Abstract: Aluminum-based composites reinforced with in-situ Al2O3, TiB2 and Al3Ti particles were prepared through reactive hot pressing from Al, B2O3 and TiO2 powders and Al, B and TiO2 powders. There is fine Al3Ti precipitation in composite fabricated by Al, B, TiO2 powders. The low cycle fatigue behavior of in-situ composites was investigated under total strain-controlled conditions at the room temperature. The composite free of precipitation Al3Ti phase exhibits a stable cyclic response at lower total strain amplitudes. The cyclic hardening in the first cycle followed by cyclic softening occurs in the composite free of precipitation at higher total strain amplitudes.The composite containing Al3Ti phase exhibits a stable cyclic response at all amplitudes adopted in the study. The sets of crack initiation are broken Al3Ti phase, the debonded interface between Al3Ti phase and matrix, and microcracks in the matrix. The cracks propagate through the matrix, passing by Al2O3 and TiB2 particles. The fatigue life of two composites can be described by the Coffin-Manson relationship.

     

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