Effects of cooling rate on microstructure, mechanical and corrosion properties of Mg-Zn-Ca alloy
(1. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China;
2. College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China;
3. School of Materials Science and Engineering, Southwest University, Chongqing 400715, China)
2. College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China;
3. School of Materials Science and Engineering, Southwest University, Chongqing 400715, China)
Abstract: Mg69Zn27Ca4 alloys with diameters of 1.5, 2 and 3 mm were fabricated using copper mold injection casting method. Microstructural analysis reveals that the alloy with a diameter of 1.5 mm is almost completely composed of amorphous phase. However, with the cooling rate decline, a little α-Mg and MgZn dendrites can be found in the amorphous matrix. Based on the microstructural and tensile results, the ductile dendrites are conceived to be highly responsible for the enhanced compressive strain from 1.3% to 3.1% by increasing the sample diameter from 1.5 mm to 3 mm. In addition, the Mg69Zn27Ca4 alloy with 1.5 mm diameter has the best corrosion properties. The current Mg-based alloys show much better corrosion resistance than the traditionally commercial wrought magnesium alloy ZK60 in simulated sea-water.
Key words: Mg-Zn-Ca alloy; bulk metallic glasses; cooling rate; mechanical properties; microstructure; corrosion resistance