Mechanical Properties of Newly Developed Age Hardenable Mg-3.2 mol%Gd-0.5 mol%Zn Casting Alloy

Abstract

A new Mg-Gd-Zn-base cast alloy was developed for high strength casting products. Effects of Zn content on microstructures and tensile strength were investigated. Both Mg-3.2%Gd-0.5%Zn-0.2%Zr (in mol%, 0.5GZ) and Mg-3.2%Gd-0.75%Zn-0.2%Zr (0.75GZ) alloys showed remarkable age hardening by precipitation of 0 phase with bco structure as similar to Mg-Gd-Y-Zr alloy. The precipitates are finer and denser than those of Mg-Gd-Y-Zn-Zr alloy by Zn and a large amount of Gd addition. Mg 3 Gd compound particles remained at grain boundaries after solution treatment. Long period stacking ordered (LPSO) phase did not form. It is considered that Mg 3 Gd particles suppressed grain coarsening during the heat treatment, and provided fine grain structure of about 30 mm in diameter. Tensile strength of the T6-treated 0.5GZ alloy was 410 MPa at room temperature and the high strength was kept by 473 K.

Enhanced mechanical properties and rolling formability of fine-grained Mg–Gd–Zn–Zr alloy produced by equal-channel angular pressing

“…The fact also indicates that GBS with dislocation viscous glides would occur in the hot-rolling sample. An additional aging treatment at 498 K illustrated that the GZ11 K alloy was significant age-hardening and the peak hardness in the 16-pass sample was attained at 119HV 0.1 after 60 h. Grain refinement strengthening, combined with the work hardening effect as well as precipitation strengthening [3,27], contribute to the high strength of the 16-pass ECAP + RT rolling alloy. Some deformation twins were shown in the optical micrograph of the hot-rolled sample at 773 K (see Fig.…”

“…The development of new casting Mg alloys with excellent mechanical properties for near-net shape products are strongly desired. The production and engineering application of Mg thin sheets required the better formability at lower temperature and reduced anisotropy of mechanical properties [3,4].…”

The influence of hot isostatic pressing on precipitates, mechanical properties of Mg-12Gd-0.8Zn-0.4Zr (wt.%) alloy manufactured by sand casting

“…According to the increasing standards for the aeronautical components, higher strength with good elongation of Mg alloys is necessary to meet the application requirements. Based on previous studies 11 – 15 , alloying is one of the most efficient methods to enhance the mechanical properties of Mg alloys and the common alloying elements are Gd and Zn element 16 – 18 . In Mg-12Gd-0.8Zn-0.4Zr (GZ1208K, wt.%) alloy 19 , the yield strength (YS) of sand-cast GZ1208K alloy is 270 MPa in T6 condition, which is almost the highest YS in sand-cast Mg alloys, and its elongation (EL) is 2.6%, which has more balanced properties (combined strength with elongation) compared to other high strength Mg alloys 1 – 5 .…”

The Influence of Holmium on the Microstructure and Hardness of Mg-Nd-Gd-Zn-Zr Alloys

“…The heavy rare earth elements (HRE) in the magnesium alloys exhibit high strengths [12]. Solution strengthening is significantly affected by the large solubility of the heavy rare earth in magnesium at high temperature.…”