Microstructure and Mechanical Properties of Mg-Al-Ca-Nd Alloys Fabricated by Gravity Casting and Extrusion Process

Abstract

The as-cast microstructure of Mg-5Al-3Ca-xNd alloys consists of equiaxed -Mg matrix, (Mg, Al) 2 Ca eutectic phase and Al-Nd rich intermetallic compounds. With the increase of Nd addition, -Mg matrix morphology was changed from dendritic to equiaxed grains due to suppression of grain growth by formation of homogeneous intermetallic compounds containing Nd dispersed at grain boundary and -Mg matrix. And the grain size of as-cast alloys was decreased as addition of Nd was increased. This eutectic phase of the extruded alloys was elongated to extrusion direction and size of this phase was redined comparing to that of as-cast alloys because of severe deformation during hot extrusion. Maximum yield and ultimate tensile strength value of the as-extruded alloys was 322 and 335 MPa at Mg-5Al-3Ca-2Nd alloy, respectively.

Mechanical Properties and Fracture Behavior of Hot Extruded Mg-5Al-3Ca-xNd Alloys at Elevated Temperature

“…At 250°C, the ductility of all alloys was dramatically increased. In our previous study [8], dynamic recrystallized fine grains less than 4 µm were observed in all extruded Nd-containing alloys. It is natural to consider that the recrystallized fine grains were attributed to the occurrence of grain boundary sliding.…”

Flame-resistant Ca-containing AZ31 magnesium alloy sheets with good mechanical properties fabricated by a combination of strip casting and high-ratio differential speed rolling methods

“…There are four major precipitation phases existing in the 0.7% Ca-AZ31: (Al,Mg) 2 Ca, β-Mg 17 Al 12 , Al 4 Mn and Φ-Mg 21 (Al,Zn) 17 . While β-Mg 17 Al 12 and Φ-Mg 21 (Al,Zn) 17 completely dissolves above approximately 450 K, (Al,Mg) 2 Ca remains stable up to 823 K, indicating that (Al,Mg) 2 Ca is the thermally stable phase. Figure 3 shows the backscattered phase is the most abundant phase.…”

“…For this reason, plastic deformation ability of the cast Mg-Al-Ca alloys is rather poor. Hot working, however, was shown to be able to improve the formability by effectively decreasing the grain size and fragmenting the coarse Al 2 Ca compounds into small particles [14][15][16][17][18][19]. The microstructure of the Mg-Ca-Al alloys [14][15][16][17][18] could be effectively refined by extrusion.…”

“…Hot working, however, was shown to be able to improve the formability by effectively decreasing the grain size and fragmenting the coarse Al 2 Ca compounds into small particles [14][15][16][17][18][19]. The microstructure of the Mg-Ca-Al alloys [14][15][16][17][18] could be effectively refined by extrusion. Watanabe et al [14] extruded a 2 wt% Ca-AM60 (Mg-6% Al-0.3% Mn) alloy prepared by conventional ingot casting and obtained the fully recrystallized microstructure composed of equiaxed grains of 15 μm and (Mg, Al) 2 Ca particles of 1-2 μm.…”

Effect of Zn and Cu Addition on Mechanical Properties of As-Extruded Mg-3Sn-1Ca Alloy

“…According to the observation of microstructure, this is closely related to the number and size of the second phase. In addition, the literature shows that the Zn-modified samples increases the possibility of prismatic slip activation during deformation, which is beneficial to adjust the strain of grain c-axis, and can also inhibit grain boundary cracking to enhance grain boundary cohesion, thus greatly improving the plasticity of the alloy [38,39]. In the Cu-modified samples, Mg 2 Cu phase is formed, and the yield strength is increased by 19.5 MPa, compared with the TXZ311alloy, but the elongation is reduced to 8.89%, which is mainly due to the high hardness and modulus of Mg2Cu phase [40].…”