微觀組織與斷裂行為
(北京工業(yè)大學 材料科學與工程學院，北京 100124)
摘 要: 采用多次循環(huán)塑性變形−原位反應方法制備Mg2Si/Mg-2Al-Zn-2Gd復合材料。采用XRD、SEM和TEM對復合材料的成分及微觀組織進行分析和觀察。結果表明：多次循環(huán)塑性變形過程對鎂合金基體組織和原位合成的Mg2Si第二相粒子均有細化和均化作用；隨著Mg2Si顆粒含量的增加，復合材料的彈性模量和屈服強度增加，同時斷裂強度和伸長率均下降；原位反應合成的Mg2Si第二相粒子與基體結合良好，材料斷裂時裂紋優(yōu)先在基體中形成，斷裂時Mg2Si第二相粒子能起到阻礙裂紋擴展的作用；Mg2Si/Mg-2Al-Zn-2Gd復合材料的強化機制主要為第二相強化和基體晶粒細化。
關鍵字: Mg2Si/Mg-2Al-Zn-2Gd復合材料；斷裂行為；多次循環(huán)塑性變形；原位合成；Mg2Si
Mg2Si/Mg-2Al-Zn-2Gd composite
（School of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China）
Abstract:The Mg2Si reinforced Mg-2Al-Zn-2Gd composite was synthesized by in-situ solid state reaction and repeated plastic deformation (RPW) process. The XRD, SEM and TEM analysis results indicate that the RPW method can significantly decrease the second phase particle size as well as the matrix crystalline size, and the elastic modulus and yield strength of the composite increase with increasing the volume fraction of Mg2Si whereas the fracture strength and strain decrease. The interface between Mg2Si and matrix is smooth, and no crack initiation source has been found on the interface. The propagation of cracks formed in matrix during fracture can be obstructed by the second phase, and the increase of mechanical properties of the composite is attributed to the dispersed Mg2Si second phase particle and the refined matrix grain size.
Key words: Mg2Si/Mg-2Al-Zn-2Gd composite; fracture behavior; repeated plastic deformation; in-situ synthesis; Mg2Si
