二次挤压对SiC_p/2009Al复合材料微观结构和力学性能的影响

来源期刊：金属学报2010年第9期

论文作者：刘振宇 王全兆 肖伯律 马宗义 刘越

文章页码：1121 - 1127

关键词：粉末冶金； 复合材料； 铝合金； 二次挤压； 贫SiC_p； 带

Key words：powder metallurgy； composite； aluminum alloy； double extrusion； SiC_p-poor band

摘    要：对粉末冶金法制备的20%SiC_p/2009Al(体积分数)复合材料进行了一次挤压和二次挤压,对2种挤压棒材微观结构的观察表明,相对于热压复合材料,挤压可以减少SiC_p团聚;而二次挤压可进一步细化SiC_p,使SiC_p沿挤压方向定向分布,增大SiC_p的长径比,但对基体合金晶粒尺寸和〈111〉织构影响不大.此外,二次挤压使SiC_p沿挤压方向的平均间距进一步增大,更易于产生近似垂直于挤压方向的贫SiC_p层,导致复合材料屈服和抗拉强度下降而延伸率增加.

Abstract: Powder metallurgy (PM),as an important method of fabricating SiC particle reinforced aluminum matrix (SiC_p/Al) composites,has advantages in obtaining good interfacial bonding and enhancing tensile strength over casting or infiltrating method.The primary process of the PM method involves mixing,compaction and subsequent secondary plastic deformation.Especially,secondary plastic deformation is an important process to destroy the oxidation film on the Al particle surfaces and enhance Al-SiC bonding.However,the incorporation of the SiC particles restricts plastic flow ability of the composite and makes it difficult to be subjected to heavy single-step plastic deformation,such as single hot extrusion,hot rolling or hot forging.Instead,multi-step deformation is a critical processing approach for the SiC_p/Al composites with low deformability.However,the previous attentions were mostly focused on single-step processing,multi-step plastic deformation of the SiC_p/Al composites was seldom discussed.In this paper,20%SiC_p/2009Al (volume fraction) composite was fabricated using a common PM method and the effects of double extrusion on the microstructure and tensile property of the composite were investigated.It is indicated that the double extrusion could refine the SiC_p size,align the SiC_p and increase the aspect ratio of the SiC_p,but did not exert critical effects of the grain size and <111> texture of the matrix.However,the average distance between the SiC_p along the extrusion direction increased after the double extrusion,more easily inducing a SiC_p-poor band which aligned approximately perpendicularly to the extrusion direction.This resulted in a decrease in the strength and an increase in the elongation along the extrusion direction.