Promoted aging precipitation behavior of TC4/GZ151K magnesium matrix composites

The precipitation behavior of TC4/GZ151K composite (Ti-6Al-4V reinforced Mg-15Gd-1Zn-0.4Zr) after solution and aging heat treatment (T6-treated) has been investigated. Quantitative measurements of precipitates revealed that nano-8 ' phase in T6-treated TC4/GZ151K composite was denser and thinner than that in T6-treated GZ151K matrix, generating higher ultimate tensile strength of composite than that of matrix (410 MPa vs. 373 MPa). it was disclosed by geometric phase analysis that there were more geometrically necessary dislocations in solutiontreated composite than that in the matrix, which was caused by different coefficient of thermal expansion between TC4 and Mg. High-density dislocations are beneficial to precipitate fine and dense 8 ' phase in the composite while low-density dislocations result in coarse and loose 8 ' phase in the matrix after aging process. This work confirmed the accelerating effect of TC4 particles on Mg-matrix's aging precipitation, which was of great significance to regulate the precipitation behavior of Mg alloy and produce high strength-ductile Mg materials.