Microstructure and Mechanical Properties of Mg-Al-Ca-Sm Alloys at High Temperature

Abstract

The aims of this research are to investigate the effect of Sm addition in Mg-Al-Ca alloys on microstructure and mechanical properties. Sm addition to Mg-5Al-3Ca based alloys results in the change from dendritic to equiaxed grain morphorlogy and formation of Al-Sm rich itermetallic compounds at grain boundary and α-Mg matrix. And these Al-Sm rich intermetallic compounds were dispersed homogeously and stabilized at high temperature. And maximum yield and ultimate strength value was obtained at Mg-5Al-3Ca-2Sm alloys at elevated temperature because of homogeneous dispersion of stable Al-Sm rich intermetallic compound at high temperature.

Effects of samarium (Sm) additions on the microstructure and mechanical properties of as-cast and hot-extruded Mg-5wt%Al-3wt%Ca-based alloys

“…2b). In our recent papers [17], it was confirmed that the ␣-Mg matrix morphology was changed from dendritic to equiaxed grains with an increase in the addition of Sm from 1 wt% to 3 wt% due to the suppression of grain growth by the formation of homogeneous intermetallic compounds containing Sm at the ␣-Mg matrix and grain boundary. To observe the eutectic phase distribution, the specimens were tilted 70 • in the SEM chamber.…”

“…1a and b), the grey and bright contrast phases were observed. The grey and bright phases were identified with the (Mg, Al) 2 Ca eutectic phase [17] and Al-Sm-rich intermetallic compounds by EDS (Fig. 1c), respectively.…”

“…The addition of Ca to Mg-Al alloys has been found to improve its mechanical properties [4][5][6][7][8][9]. This is because the more stable Mg 2 Ca and/or Al 2 Ca Laves phase or (Mg, Al) 2 Ca phase are precipitated by a eutectic reaction during solidification of Mg-Al-Ca alloys instead of the ␤ phase (Mg 17 Al 12 ). Also, the addition of Ca builds up networks of eutectic intermetallic compounds at grain boundaries in Mg-Albased alloys, which give rise to high creep resistance.…”

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

“…Microstructure of as-cast alloys with Nd additons consists of -Mg matrix and eutectic phase and Nd containing intermetallic compounds. These eutectic phases and Nd containing intermetallic compounds with bright contrast were identified to (Mg, Al) 2 Ca phase 18,19) and Al-Nd rich intermetallic compound by SEM-EDS analysis, respectively. In microstructure of Nd containing alloys, Al-Nd rich intermetallic compounds were observed at both grain boundary and -Mg matrix.…”

Microstructure and Dynamic Ultra-Micro Hardness of the As-Cast and Extruded Mg-Al-Ca-Sm Alloys

“…Recently, the addition of Ca to Mg-Al alloys has been found to improve the mechanical properties. This is because the more stable Mg 2 Ca and/or Al 2 Ca Laves phase or (Al, Mg) 2 Ca phase are precipitated by an eutectic reaction along the grain boundaries during the solidification of Mg-Al-Ca alloys instead of the Al 12 Mg 17 phase [1][2][3]. Moreover, it is well known that the addition of rare earth (RE) elements is an effective way to improve the mechanical properties of magnesium alloys at elevated temperatures.…”