Effect of the Ca content on the microstructural evolution of Ca containing AZ31 cast alloys

Abstract

Microstructural changes with varying amounts of Ca in cast AZ31-xCa (x: 0.7 wt.%, 2.0 wt.%, 5.0 wt.%) alloys were investigated. According to transmission electron microscopy (TEM) analyses, it was experimentally confirmed that the C36-(Mg,Al)2Ca phase with a di-hexagonal structure formed at interdendritic regions in as-cast AZ31 alloys with no more than 2 wt.% Ca. On the other hand, as the Ca content exceeded 2 wt.%, the lamellar structure consisting of the α-Mg phase and the Mg2Ca phase with a C14 structure formed at interdendritic regions instead of C36 phase. Plate-like Al2Ca precipitates with a C15 structure also formed on the basal plane inside the α-Mg grains.

Effect of Ca addition on the damping capacity of Mg-Al-Zn casting alloys

“…2(d), (h)). This microstructural change is in good agreement with previously reported results, and is typical of Mg-Al-Ca alloys [13][14][15][16]. The microstructure refinement caused by Ca addition is related to the strong segregation behavior of the Ca solutes, that induces constitutional undercooling in a diffusion layer in front of the advancing solid/liquid interface and restrains the growth of the cells [18].…”

“…This result is significant because Ca is a useful alloying element for improving the damping properties of Mg-Al based alloys without sacrificing their strength values [13,14]. The present study aims to investigate the influence of Ca addition on the damping capacities of AZ91-(0~2)%Ca alloys, motivated by the fact that Ca contributes to changes in microstructural features such as grain size, phase constituents, and phase content [13][14][15][16]. Similar to other mechanical properties, damping capacity is greatly affected by the microstructure, and thus it is reasonable to expect that extensive addition of Ca can lead to an alternation of the damping capacity of MgAl alloys.…”

Influence of the Al2Ca phase on microstructure and mechanical properties of Mg–Al–Ca alloys

“…Some reports on grain refining efficiencies of Ca in MgeAl have been published [18e21]. On the other hand, according to the previous researches [22,23], Al 2 Ca is proved to be a eutectic phase during solidification process. Furthermore, Ca features a stronger affinity to Al [18].…”

Effect of extrusion speed on microstructure and mechanical properties of Mg-Al-Ca-Sn alloy

“…Mg-Al alloy can be used as the main component of commercial magnesium alloy because of its high strength and plasticity, excellent castability, low price and good corrosion resistance [21]. Ca is a promising element with low density and price in magnesium alloys, which can improve its high-temperature performance, creep resistance and refine grain size [22][23][24][25][26]. In the Mg-Al-Ca ternary alloy, with the difference of Ca/Al, Laves phases (Mg, Al) 2 Ca (C36), Al 2 Ca and Mg 2 Ca (C14) with high temperature stability will be produced at grain boundaries [27].…”