Effects of heat treatment on microstructure and mechanical properties of Mg-8Gd-3Y-0.5Zr (wt.%) alloy fabricated by semi-continuous casting

China Foundry

Qu-dong Wang¹  Huan Wang¹  Jun Yang¹ 

[1] National Engineering Research Center of Light Alloys Net Forming and State Key Laboratory of Metal Matrix Composite, Shanghai Jiao Tong University, Shanghai 200030, China;

关键词: Mg-Gd-Y-Zr alloys;    semi-continuous casting;    heat treatments;    mechanical properties;    fracture;   

DOI  :  

来源: DOAJ

【 摘 要 】

The microstucture, mechanical properties and fracture behaviors of semi-continuous cast Mg-8Gd-3Y-0.5Zr (wt.%, GW83K) alloy after different heat treatments were investigated. Almost all the eutectic compounds were dissolved into the matrix and there was no evident grain growth after optimum solution treatment at 500 °C for 4 h. Further ageing at low temperatures led to significant precipitation hardening, which strengthened the alloy. Peak-aged at 200 °C, the alloy had the highest ultimate tensile strength (UTS) and lowest elongation at 395 MPa and 2.8%, respectively. When aged at 225 °C for 15 h, the alloy exhibited prominent mechanical performance with UTS and elongation of 363 MPa and 5.8 %, respectively. With regard to microstructure and tensile properties, the processes of 500 °C, 4 h + 225 °C, 15 h are selected as the optimal heat treatment conditions. The alloy under different conditions shows different fracture behaviors: in the as-cast alloy, a quasi-cleavage pattern is observed; after solution treatment, the alloy exhibits a trans-granular quasi-cleavage fracture; after being peak-aged at 200 °C and 225 °C, the fracture mode is a mixed mode of trans-granular and inter-granular fracture, in which the inter-granular mode is dominant in the alloy peak-aged at 200 °C.

【 授权许可】

Unknown