挤压温度对真空吸渗挤压C_(sf)/Mg复合材料制备工艺的影响  

Effect of Extrusion Temperature on Fabrication of C_(sf)/Mg Composite by Extrusion Directly Following Vacuum Pressure Infiltration Process

作　　者：关俊涛[1] 齐乐华[1] 刘健[1] 周计明[1] 

机构地区：[1]西北工业大学机电学院,西安710072

出　　处：《机械工程学报》2012年第14期25-31,共7页Journal of Mechanical Engineering

基　　金：国家自然科学基金(50972121);西北工业大学博士创新基金(cx201011);西安工业大学科技创新基金(2010KJ0202);凝固技术国家重点实验室基金(SKLSP201103)资助项目

摘　　要：真空吸渗挤压工艺是近年来开发的一种金属基复合材料成形新工艺,研究挤压温度对真空吸渗挤压Csf/Mg复合材料变形规律、成形性及微观组织的影响规律,并分析热裂纹产生的内在原因。结果表明,在380～420℃的温度范围内,随着挤压温度的升高,最大成形载荷逐步降低,载荷—位移曲线中稳定挤压阶段逐渐缩短。在较低的挤压温度下实施挤压变形时,制件前端出现大量连续的孔隙缺陷,且纤维折断严重。提高挤压温度可以减少缺陷数目,降低纤维折断程度,但过高的挤压温度会使复合材料表面出现热裂纹缺陷,且热裂纹沿挤压方向呈逐渐严重的趋势。塑性变形引起的变形区坯料温度升高是复合材料表面出现热裂纹的主要原因。挤压速度与合金凝固速度的协调匹配是降低热裂纹出现概率的可行手段。在挤压温度为390～400℃、挤压速度为2～3 mm/s的条件下,可以一次成形出质量、良好的Csf/Mg复合材料制件。CstCMg composites are fabricated by extrusion directly following vacuum pressure infiltration technique, the effect of extrusion temperature on the deformation law, formability and microstructure of the composites are investigated, the causes of hot cracking are analyzed. In the range of 380-420 ℃, with the increasing extrusion temperature, the maximal forming pressure decreases gradually and the steady extrusion stage shorts in the extrusion pressure-displacement curves. At lower extrusion temperature, many macro cracks occur at the front end and carbon fibers are broken severe. The fiber breakage rate decreases with increasing extrusion temperature, but overhigh extrusion temperature may lead to hot cracks on the surface of composite bars, and the hot cracks become severe along the extrusion direction. Temperature rise due to plastic deformation is the main reason for the hot cracks on the composite surface. The matching between the extrusion temperature and alloy solidification rate is an efficient way to minimize the risk of the hot cracking. With extrusion temperature ranging from 390 ℃ to 400℃, extrusion speed of 2-3 mm/s, Cs/Mg composites with high quality are obtained.

关 键 词：挤压 复合材料 温度 成形性 微观组织 

分 类 号：TG376[金属学及工艺—金属压力加工] TB331[一般工业技术—材料科学与工程]