热暴露对SiCf/Ti-6Al-4V复合材料热膨胀行为的影响

Effect of Thermal Exposure on the Thermal Expansion Behavior of SiCf/Ti-6Al-4V Composite

摘要:

研究了热暴露对SiCf/Ti-6Al-4V复合材料热膨胀行为的影响。对基体合金、制备态复合材料、经900 ℃热暴露10, 25及75 h的复合材料的热膨胀行为进行了实验测量。结果表明，无论纵向和横向，热暴露的复合材料其热膨胀系数均高于制备态复合材料。且无论纵向和横向，经900 ℃热暴露10和75 h的复合材料热膨胀系数均高于经900 ℃热暴露25 h的复合材料。这是因为经900 ℃热暴露25 h的复合材料拥有较为合适的界面反应。另外，在对复合材料纵向热膨胀系数进行预测时，因为Schapery模型在整个加热过程中都考虑了热拉伸残余应力对复合材料热膨胀系数的影响，因此在CTE曲线的高温阶段，预测值低于实验值

Abstract:

SiCf/Ti-6Al-4V composites were used to study the effects of thermal exposure on the thermal expansion behavior of composites. The expansion behaviors of the matrix alloy, as-processed composite, and composites exposed at 900 oC for 10, 25 and 75 h were investigated by coefficients of thermal expansion (CTE) test. The results indicate both in longitudinal and transverse direction, the CTE of the exposed composite is higher than that of the as-processed composite. The CTEs of the specimens exposed at 900 oC for 10 and 75 h are higher than that of the specimen exposed at 900 oC for 25 h, no matter in longitudinal or transverse direction. It can be attributed to that there is an appropriate interfacial reaction for the composite exposed at 900 oC for 25 h. Because the prediction of Schapery’s model for CTE of composite includes the influence of thermal tensile residual stress in matrix at the whole heating process, the CTE results predicted by Schapery’s model are lower than the real CTE obtained from experiments at the high temperature stage of the CTE curve