Effects of Ca combined with Sr additions on microstructure and mechanical properties of AZ91D magnesium alloy

Abstract

Weight reduction to improve automobile fuel economy has triggered renewed interest in magnesium. The effects of Ca/Sr separate and composite additions to AZ91D magnesium alloy on its microstructure and mechanical properties have been investigated. The results indicate Ca can refine both the grain and eutectic phase of AZ91D magnesium alloy. Sr hampers microstructure refinement when composite Ca/Sr additions are made. In addition, separate Ca additions to AZ91D magnesium alloy increase yield strength but decrease elongation of this alloy. By adjusting the Ca/Sr composite proportions, additions to AZ91D magnesium alloy are able to improve both microstructure and mechanical properties of the alloy.

Development of a new magnesium alloy ZW21

“…Sn and Ca exist in the form of interdendritic particles (Fig. 5g and h), which is in accordance with the available results that the extra Sn and Ca can form eutectic Mg 2 Sn phase and Ca-rich brittle phase in interdendritic regions respectively besides some of them dissolve in the a-Mg phase [25,27,30,31,33,37]. Due to the amounts of these phases are very limited, the XRD does not detect their existence under its sensibility.…”

“…Ca can reduce the oxidation of magnesium alloy melts and always is used in ignition proof magnesium alloys [30]. In addition, Ca has significant grain refinement and thus improves mechanical properties such as yield strength, hardness and creep resistance [30][31][32]. Especially, 0.2% Ca has good effect on improving UTS and yield strength of Mg-Zn-RE alloys [33].…”

Environment-induced fatigue cracking behavior of aluminum alloys and modification methods

“…In these application fields, the general comprehensive requirements for components include high fatigue strength, excellent corrosion resistance, and good wear protection performance. However, the high fatigue strength is usually achieved by proper material selections, which is accompanied by a high tensile strength and high ductility of material, but these often result in an accompanying high cost (Dahle & Arnberg, 1997;Tang, Wang, Li, & Zeng, 2005;Wang & Fan, 2006;Wang, Lu, & Wang, 2004a, Wang, Liang, Fan, & Zhang, 2006b. Moreover, excellent corrosion resistance is usually achieved by various protective coatings to avoid the environmentally corrosive damage of substrate materials.…”

Influence of Multi-Holes on Fatigue Behaviors of Cast Magnesium Alloys Based on In-Situ Scanning Electron Microscope Technology

“…In addition, these alloys have been widely used for the plates with small holes in the automotive and aircraft industry in order to be riveted [ 4 , 5 ]. Therefore, it has stimulated the substantial interest in understanding their structural integrity and service safety of components by using the magnesium alloys including the microstructural characteristics and mechanical properties in the last decade [ 6 , 7 , 8 ], enhancing strength and thermal crack resistance of cast magnesium alloys [ 9 , 10 , 11 ], the improving elongation and low-cycle fatigue (LCF) behaviors of magnesium alloys by means of grain refinement and hot-rolled treatment methods in which the deformation mechanism of AZ31 or AZ91 alloy depends on the grain size [ 12 ] and pre-compression deformation process but these magnesium alloys are most limited in the deformed magnesium aluminum alloys, especially AZ31 alloy [ 13 , 14 , 15 ]. When the average grain (α-phase) size is about 1–2 μm, the coupling mechanism of rolling and sliding deformation of these grains occurred under the applied tensile loads so that the elongation of AZ31 alloy has been more incremental than that for the only sliding deformation mechanism of AZ31 alloy with over than 50 μm of grain size [ 12 ].…”