The Microstructure and Mechanical Properties of As-cast Mg-10Gd-3Y-xZn-0.6Zr (x = 0, 0.5, 1 and 2 wt%) Alloys

Abstract

The microstructure, mechanical properties and fracture behavior of as-cast Mg-10Gd-3Y-xZn-0.6Zr (x = 0, 0.5, 1 and 2 wt%) alloys have been investigated by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and tensile tests. The experimental results reveal that the microstructure of the alloy without Zn contains α-Mg and Mg 24 (Gd,Y) 5 phase, the microstructure of the alloy with 0.5% Zn contained of α-Mg, (Mg,Zn) 3 (Gd,Y) and Mg 24 (Gd,Y,Zn) 5 phase, whereas when Zn content was 1% and 2%, the Mg 12 (Gd,Y)Zn phase and some needle-shaped stacking faults notably appear and the Mg 24 (Gd,Y,Zn) 5 phases completely disappear. Moreover, a new 18R long period stacking ordered (LPSO) phase is observed in grain boundaries with increasing Zn content up to 2%. The tensile tests indicate that the alloy containing 0.5% Zn shows the optimal mechanical properties and the ultimate tensile strength (UTS), yield strength (YS) and elongation are 228MPa, 172MPa and 5.1%, respectively. As indicated by fracture analyses, the fracture modes of the alloys with 0%, 1% and 2% Zn are brittleness transcrystalline fracture, and the tensile fracture mode of 0.5% Zn alloy is typical tough transgranular fracture.

Effect of Zn addition on the microstructures and mechanical behaviors of As-cast Mg-2.5Y-1Ce-0.5Mn alloy

“…In the point of plastic instability, the Alloy IV shows the largest strain hardening ability while the Alloy I exhibits the lowest strain hardening ability. Figure 6 compares the ultimate tensile strength s UTS ( ) and elongation d ( ) of present as-cast Mg-2.5Y-1Ce-0.5Mn-xZn (x=0, 1, 3, 5 wt%) alloys with the published results of tensile tests in other as-cast Mg-RE or Mg-RE-Zn alloys [10,16,[19][20][21][22][23][24][25][26][27][28][29][30]. It is notable that the other as-cast alloys exhibit various s UTS values in a wide range while most of their d values are lower than 8%.…”

Investigation of temperature-induced wear transition of an Mg-10Gd-1.4Y-0.4Zr alloy under non-lubricated sliding conditions

“…Furthermore, they can be significantly strengthened by heat treatments such as solid solution hardening and precipitation hardening [6][7][8]. Many research works have been made on Mg-Gd-Y-Zr alloys regarding microstructure evolution, grain refinement, precipitation behavior, mechanical properties, flow behavior as well as influence of addition of elements such as Y and Zn [9][10][11][12][13][14][15][16]. Generally, commercial Mg alloys such as AZ91D, AM50A and AM60B are currently limited to structural components working within a very limited temperature range, since unstable β-Mg 17 Al 12 phase in Mg alloys is greatly softened at elevated temperatures above 120°C.…”