热循环对SiCp／MoSi_2复合材料性能的影响

研究了热循环对ＳｉＣｐ／ＭｏＳｉ_２复合材料抗弯强度和断裂韧度的影响，并测定了材料的宏观残余应力。实验材料是用热压方法制备的ＭｏＳｉ_２和不同体积百分数（１０，２０，３０ｖｏｌ％）ＳｉＣ_ｐ增强ＭｏＳｉ_２复合材料。实验结果表明，复合材料的抗弯强度和断裂韧度都随ＳｉＣ含量的增加而增加，经过热循环以后，四种材料的抗弯强度都有不同程度的增加，而断裂韧度则下降约２０％左右。这是由于材料经过热循环以后，造成ＳｉＣｐ和ＭｏＳｉ２界面结合过强和基体晶界过弱。尽管ＳｉＣ_ｐ和ＭｏＳｉ_２热膨胀系数相差很大，但在复合材料中未发现由此而产生的裂纹和宏观残余应力。

Effects of Thermal Cycle on Mechanical Properties of SiC Particle Reinforced MoSi2 Composites

Composites of MoSi2 reinforced with various volume fractions(10, 20, 30 vol%)of SiC particles were fabricated by hot pressing(HP) . Comparative mechanical tests, including measurement of flexure strength and fracture toughness at room temperature have been taken between SiCp/MoSi2 composites before and after thermal cycle treatment. It is shown that both the strength and fracture toughness increase with the volume fraction of the SiC particle. After thermal cycle, the strength of the materials changes a little and the toughness decreases by about 20% due to the over strong interface of SiCp/MoSi2 and the weakening in the grain boundary of the matrix. Some strengthening and toughening mechanisms in SiC/MoSi2 composites are also pointed out.