To improve the comprehensive mechanical properties of Mg-10Zn-5Al-0.1Sb magnesium alloy, different amount of Ce-rich rare earth （RE） was added to the alloy, and the effect of RE addition on the microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb alloy was investigated by means of Brinell hardness measurement, scanning electron microscopy （SEM）, energy dispersive spectroscope （EDS） and X-ray diffraction （XRD）. The results show that an appropriate amount of Ce-rich rare earth addition can make the AI4Ce phase particles and CeSb phase disperse more evenly in the alloy. These phases refine the alloy＇s matrix and make the secondary phases [τ-Mg32（AI,Zn）49 phase and φ-Al2MgsZn2 phase] finer and more dispersive, therefore significantly improve the mechanical properties of the Mg-10Zn-5AI-0,1Sb alloy. When the RE addition is 1.0 wt.%, the tensile strengths of the alloy both at room temperature and 150℃ reach the maximum values while the impact toughness is slightly lower than that of the matrix alloy. The hardness increases with the increase of RE addition.
You ZhiyongZhang ZhaoguangZhang JinshanWei Yinghui
The corrosion fatigue behavior of epoxy-coated Mg-3Al-1Zn alloy was investigated in air and 3.5 wt%NaCl solution. Epoxy coating as a new method was used to improve the corrosion fatigue property of the material.Results show that the fatigue limit（FL） of the coated specimens is higher than that of the uncoated specimens in3.5 wt% NaCl solution because of the strengthening and blocking functions of the epoxy coating. The FL of the coated specimens in 3.5 wt% NaCl solution is as high as that in air. It implies that the coated specimens are not as sensitive to the environment as the magnesium alloy. The low tensile strength and the short elongation of the pure epoxy coating lead to that the fatigue crack of the coated specimen is always initiated from the epoxy-coating film Pores and pinholes accelerate the fatigue crack initiation process. Pinholes are caused by the corrosion reactions between the epoxy coating and the NaCl solution.
Xiu-Li HeYing-Hui WeiLi-Feng HouZhi-Feng YanChun-Li GuoPeng-Ju Han
To improve the strength, hardness and heat resistance of Mg-Zn based alloys, the effects of Cu addition on the as-cast microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb high zinc magnesium alloy were investigated by means of Brinell hardness measurement, scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, XRD and tensile tests at room and elevated temperatures. The results show that the microstructure of as-cast Mg-10Zn-5AI-0.1Sb alloy is composed of α-Mg, τ-Mg32（Al, Zn）49, Ф-Al2MgsZn2 and Mg3Sb2 phases. The morphologies of these phases in the Cu-containing alloys change from semi-continuous long strip to black herringbone as well as particle-like shapes with increasing Cu content. When the addition of Cu is over 1.0wt.%, the formation of a new thermally-stable Mg2Cu phase can be observed. The Brinell hardness, room temperature and elevated temperature strengths firstly increase and then decrease as the Cu content increases. Among the Cucontaining alloys, the alloy with the addition of 2.0wt.% Cu exhibits the optimum mechanical properties. Its hardness and strengths at room and elevated temperatures are 79.35 HB, 190 MPa and 160 MPa, which are increased by 9.65%, 21.1% and 14.3%, respectively compared with those of the Cu-free one. After T6 heat treatment, the strengths at room and elevated temperatures are improved by 20% and 10%, respectively compared with those of the ascast alloy. This research results provide a new way for strengthening of magnesium alloys at room and elevated temperatures, and a method of producing thermally-stable Mg-10Zn-5Al based high zinc magnesium alloys.
You ZhiyongZhang YuhuaCheng WeiliZhang JinshanWei Yinghui
