热机械循环对B/Al复合材料拉伸性能及显微结构的影响

Effects of thermal-mechanical cycling on tensile properties and microstructure of B/Al composite

热机械循环是复合材料所面临的苛刻空间环境因素.对B/Al复合材料进行温度变化范围为-125～125℃,外加拉伸载荷为30MPa的热机械循环试验,通过室温拉伸试验测量了B/Al复合材料的拉伸性能,利用SEM及TEM分析了复合材料的拉伸断口形貌及显微结构,研究了热机械循环对B/Al复合材料拉伸性能及显微结构的影响.研究表明,热机械循环造成了B纤维与Al基体之间界面的弱化,产生了可测的弹性模量的降低;同时,引起基体塑性应变,造成基体内位错密度增加.在热机械循环初期,B/Al复合材料的抗拉强度是增加的,但随即随热机械循环周次的增加而下降.

Thermal-mechanical cycling（TMC） in space has strong effects on structural composites.The tensile properties of B/Al composite were measured at room temperature before and after thermal-mechanical cycling.The effects of TMC on microstructure and tensile fracture behavior of B/Al composite were studied by transmission electron microscopy（TEM） and scanning electron microscopy（SEM）.Results show that the fiber/matrix interfaces are degraded during TMC,causing a measurable decrease of the Young＇s modulus of the B/Al composite.The TMC induces the generation of dislocation in the aluminum matrix and the dislocation density increases with the increasing cycles.The ultimate tensile strength of the composite increases with the cycles in the early stage of TMC,but subsequently decreases after further TMC.