原位自生20vol.％TiCP/LD7Al基复合材料蠕变的应力指数和门槛应力

在523 K，573 K和623 K恒应力压缩条件下研究了原位自生20vol%TiC_p/LD7Al基复合材料和LD7Al合金的高温蠕变行为.对蠕变速率与外加应力在双对数坐标中进行拟合，获得了复合材料和基体铝合金的应力指数；通过在幂率方程中引入有效应力（σ-σ₀），对实验数据进行线性回归外推至零蠕变速率得到相应的门槛应力.实验结果显示，复合材料的应力指数和门槛应力均高于LD7Al合金.TiC颗粒的存在，明显改善了LD7Al合金的高温蠕变 关键词： p/LD7Al基复合材料')" href="#">TiC_p/LD7Al基复合材料 蠕变 应力指数 门槛应力

Stress exponent and threshold stress of in situ TiC_p/LD7Al matrix composite in creep

The elevated temperature creep behavior of in situ 20vol%TiC_P/LD7Al matrix composite and LD7Al alloy was investigated under the condition of constant compressive stress at 523 K,573 K and 623 K,respectively.The stress exponents of the composite material and the matrix aluminium alloy were obtained by fitting the creep rate and the applied stress in log-log plot,respectively.By introducing an effective stress(σ-σ_0)to the power equation and extroplating the linearly-regressed experemental data to zero creep rate,the threshold stresses were obtained.The results showed that both the stress exponents and the threshold stresses of the composite were higher than those of LD7 Al,indicating that the presence of TiC particles significantly improved the elevated temperature creep property of LD7Al.By introducing a threshold stress,the high-temperature creep behavior of the composite can be explained by the cooperative effect of the dislocation-climbing and the particle hindrance to the matrix deformation.