(TiB_2-TiC)/Al复合材料的蠕变行为研究

Study on Creep Behavior of(TiB_2-TiC)/Al Composites

以活塞用铝硅合金为基体,采用原位生成法制备了3种铝基复合材料(0.1wt%TiB_2、0.03wt%TiC和(0.1wt%TiB_2+0.03wt%TiC)),测试了这3种材料在350℃、25～32 MPa载荷下的蠕变性能,观察了损伤部位的显微组织。结果表明,这3种复合材料的蠕变速率均随着载荷的增加而增大。其中,0.03wt%TiC/Al和0.1wt%TiB_2/Al复合材料的抗蠕变性能优于(0.1wt%TiB_2+0.03wt%TiC)/Al复合材料,且这两种材料的蠕变断裂形式均为准解理和部分韧窝的混合型断裂;在Ti B_2和Ti C共同作用时,α-Al晶粒细化明显,晶界比表面积增大,晶界滑移显著,(0.1wt%TiB_2+0.03wt%TiC)/Al复合材料的蠕变塑性和蠕变抗力均下降,蠕变断裂机理为沿晶断裂。

Three aluminum-based composites(0.1wt%TiB2,0.03wt%TiC and(0.1wt%TiB2+0.03wt%TiC))were prepared by in-situ formation method using an aluminum-silicon alloy as a substrate.The creep properties of the three materials under25-32MPa loading at 350℃were tested,and the microstructure of the damage site was observed.The results show that,the creep rates of these three composites increase with the increase of load.Among them,the creep resistance of 0.03wt%TiC/Al and 0.1wt%TiB2/Al composites is better than that of(0.1wt%TiB2+0.03wt%TiC)/Al composites.In addition,the creep rupture form of both materials is the mixed type fracture of the cleavage and partial phloem.Under the interaction of Ti B2and Ti Cα-Al grain refines,grain boundary specific surface area obviously increases,and grain boundary obviously slip,and creep plasticity and the creep resistance of(0.1wt%Ti B2+0.03wt%Ti C)/Al composites are decreased,and the creep fracture mechanism is intergranular fracture.