Effects of reheating temperature and time on microstructure and tensile properties of thixoforged AZ63 magnesium alloy

Abstract

The effects of two main processing parameters such as reheating temperature and reheating time on microstructure and tensile properties of thixoforged AZ63 magnesium alloy have been investigated. The results indicate that these two parameters all have large effects on the microstructure and tensile properties. However, in contrast, the effects of the reheating temperature on liquid fraction and liquid composition of semisolid ingot, and thus the subsequent solidification behaviour and plastic deformation during thixoforging, are larger than those of the reheating time. Therefore, the effects of the former parameter on the microstructure and tensile properties are relatively larger than those of the latter parameter. It is also just this reason that the fracture regime during tensile testing varies as the reheating temperature rises, while the regime always maintains transgranular mode with the variation of the reheating time. Stress concentration that results from the plastic deformation obviously affects the tensile properties, while the primary particle size or grain size only has small effect. The appropriate reheating technique is the heating for 60 min at 595°C when mould temperature is maintained at 350°C. The ultimate tensile strength and elongation of the resulting alloy are up to 310 MPa and 10·7 respectively.

Effect of heat treatment on corrosion behavior of AZ63 magnesium alloy in 3.5 wt.% sodium chloride solution

“…Besides, they found that the ignition temperatures increase with increasing melt viscosities. Chen et al [30,31] investigated the impact factors on microstructure and tensile properties of thixoforged AZ63 magnesium alloys. The results suggested that the mould temperature affected the solidification behavior, plastic deformation and recrystallization during thixoforging by changing solidification rate.…”

Tensile Properties and Fracture Behavior of a Powder-Thixoformed 2024Al/SiCp Composite at Elevated Temperatures

“…Moreover, both the size and number of the cavities increased as the temperature elevated. It is known that SSS were the weak points of the thixoformed materials because shrinkage porosities and pores always existed in these structures [40]. Meanwhile, its compatible deformation ability was poor due to the existence of hard and fragile eutectics and SiC p .…”

“…Therefore, the debonding of SiC p as well as void nucleation and growth were the main fracture mechanisms in the composite at high temperature, and increasing the testing temperature (less than 250 • C) induced relatively improved ductility of the composite, but the elongation decreased when the temperature exceeded 250 • C due to the extensive cavity formation. pores always existed in these structures [40]. Meanwhile, its compatible deformation ability was poor due to the existence of hard and fragile eutectics and SiCp.…”

A Comparative Characterization of the Microstructures and Tensile Properties of As-Cast and Thixoforged in situ AM60B-10 vol% Mg2Sip Composite and Thixoforged AM60B

“…Grain growth by coalescence by grain boundary migration is dominant for short times after the liquid is formed, and Ostwald ripening is dominant for longer times [22]. This is a common phenomenon in thixoforged materials [23][24][25]. The Mg2Si particles and the liquid might be engulfed by the merged primary α-Mg grains, so Mg2Si particles or the eutectic β phase would distribute inside the primary α-Mg grains in the thixoforged specimens.…”