热暴露对B/Al复合材料性能的影响

摘要

对经300℃、500℃高温热暴露的B/Al(LF6)复合材料的力学性能进行了研究，实验结果表明材料在300℃下热暴露时，性能下降速度较慢，100h后强度保留率约为76％，延伸率保留率为74％。而在500℃下热暴露时，5 h以上强度就有明显降低。高温长时间热暴露后复合材料的断裂也从累积型转变为典型的非累积型断裂。通过透射电镜(TEM)及扫描电镜(SEM)对固态热压制造态和高温热暴露的界面状况进行了分析，认为界面反应是造成B/Al复合材料力学性能下降的主要原因。%Mechanical properties of the B/A1 composites exposed in hot air up to 300℃C,.500＄ are investigated.Experimental results show that thermal treatment at 300℃ may result in less decrease with tensile strength remained about 72% ,and ultimate strain remained 74% after 100 h ,for example ,but thermal treatment at 500℃ only for 5 h can significantly decrease the tensile strength of the B/Al composites.Failure mode of the composite also changes from cumulative to typical noncumulative after long time exposure at 500℃.Interfacial microstructure and phase composition of the B/Al composite before and after exposure is studied by TEM and SEM.It is showed that interfacial reaction is the main reason of decrease ofmechanical properties of the B/M composites.