SiCP/ 6061Al 合金复合材料的高温单轴棘轮行为及其时间相关特性

对T6 热处理后的SiC_P / 6061Al 合金复合材料的高温(300 ℃) 单轴应变循环特性和棘轮行为进行了实验研究, 讨论了具有两种颗粒体积分数的复合材料在高温下不同加载条件时的循环软/ 硬化特性和棘轮行为特征。实验研究表明: 颗粒增强金属基复合材料宏观上表现出与金属材料相类似的应变循环特性和棘轮变形规律, 即复合材料在非对称应力循环下也将产生一定的棘轮变形, 并随应力幅值和平均应力的增加而增加; 颗粒的引入使复合材料抵抗棘轮变形的能力增强, 棘轮变形随颗粒体积分数的升高而下降; 在高温下棘轮行为体现出明显的时间相关特性, 即棘轮应变值明显依赖于加载率和峰值保持时间, 并具有明显的蠕变-棘轮交互作用。在对该类复合材料的棘轮行为进行本构描述时必须考虑复合材料的微结构特征、加载条件以及时间效应等的影响。 

Uniaxial ratcheting of SiCP/ 6061Al alloy composites and itstime-dependence at high temperature

The uniaxial st rain cyclic characteristics and ratcheting behavior of T6-t reated SiCP / 6061Al alloy composites were experimentally studied at high temperature (300 ℃) . The cyclic sof tening/ hardening feature and ratcheting behavior of the composites containing two kinds of particulate volume f ractions were discussed under differentloading conditions at high temperature. It is shown that the particulate reinforced metal mat rix composites showsimilar st rain cyclic characteristics and ratcheting behavior to those of metals on a macro-scale. Namely , the ratcheting also occurs in the composites under asymmet rical cyclic st ressing , and the ratcheting st rain increases with theincrease of the st ress amplitude and mean st ress ; however , the addition of SiC particulates into the mat rix increasesthe resistance of the composites to ratcheting , and the ratcheting st rain decreases with the increase of the volumef raction of SiC particulates ; at 300 ℃, the ratcheting has great time2dependence , i. e. , the ratcheting st rain dependsgreatly on the st ressing rate and hold-time at peak st ress , and an interaction of creep and ratcheting is remarkable.The effect s of microst ructure features of the composite , loading condition and time on the ratcheting should be wellconsidered when t rying to const ruct a constitutive model to describe such ratcheting.