In-situ observation for the formation and propagation of cracks in YAl / Mg-Li-Al composite during dynamic tension
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摘要: 通过 SEM中静载动态拉伸 , 原位观察和研究了搅拌铸造法制备的 YAl 2P/ Mg-Li-Al 基复合材料裂纹的萌生及扩展机制。结果表明 , 微裂纹萌生位置主要为复合材料的铸造缺陷处、 复合材料的基体中以及颗粒/基体界面处 , 并以在复合材料基体中萌生为主。微裂纹的扩展主要在基体和 YAl 2颗粒/基体界面处进行。主裂纹的长大方向具有选择性 , 裂纹主要沿颗粒贫化区与颗粒富集区的交界处开裂 , 主裂纹扩展到一定程度后 , 试样全面失稳而迅速断裂。基体的断裂失效在 YAl 2P/ Mg2Li2Al复合材料拉伸断裂过程中起很大作用。
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关键词:
- Mg-Li-Al基复合材料 /
- YAl 2颗粒 /
- 断裂 /
- 原位拉伸
Abstract: YAl 2P/ Mg-Li-Al composite was prepared by stir-casting. The mechanisms of the crack forming and the
propagation were investigated during the dynamic tension under the static load by SEM. The result s show that the microcracks appear at the casting defect s , in the Mg-Li-Al mat rix and on the interface of YAl 2P/ Mg-Li-Al
composite. The microcracks propagated mainly in mat rix or along the particle/ mat rix interface. The dominant crack is mainly developed along the boundary between the particle-dense regions and particle2f ree regions , and the samples lose the stability and f racture rapidly af ter the cracks propagating to some extent . The mat rix failure may play a significant role in the failure mechanism of YAl 2P/ Mg-Li-Al composite.-
Key words:
- Mg-Li-Al mat rix composites /
- YAl 2 particles /
- f racture /
- in-situ tension
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