Effect of Al Addition on Grain Refinement and Phase Transformation of the Mg-Gd-Y-Zn-Mn Alloy Containing LPSO Phase

Abstract

The effect of 0–1.0 at.% Al additions on grain refinement and phase transformation of the Mg-2.0Gd-1.2Y-0.5Zn-0.2Mn (at.%) alloy containing a long period stacking ordered (LPSO) phase was investigated in this work. The addition of Al promoted the formation of the Al2RE phase in the Mg-2.0Gd-1.2Y-0.5Zn-0.2Mn (at.%) alloy, and the dominant secondary phases in the as-cast Mg-2.0Gd-1.2Y-0.5Zn-0.2Mn-1.0Al (at.%) alloy were the Mg3RE phase, LPSO phase, and Al2RE phase. With increased Al addition, the area fraction of the Al2RE phase increased monotonously, while the area fraction of LPSO phase and Mg3RE phase decreased gradually. The orientation relationship between the Al2RE phase and the α-Mg matrix was determined to be <112>Al2RE//<112¯0>α-Mg, {101}Al2RE//{101¯0}α-Mg, which was not affected by Zn and Mn concentrations in the Al2RE phase. Since the Al2RE particles with a size more than 6 μm located at the center of grains could act as nucleants for α-Mg grains, the average grain size of the as-cast alloys decreased from 276 μm to 49 μm after 1.0% Al addition. The effect of the Al addition on the grain refinement of the Mg-2.0Gd-1.2Y-0.5Zn-0.2Mn alloy was comparable to that of the Zr refined counterpart.

Effect of cooling rate on microstructure and mechanical properties of Mg-9Gd-4Y-1Zn-1Al alloy

“…Gibbs free energy difference between Al and RE is the smallest in Mg-RE-Al alloys [33], so Al and RE react preferentially, which leads to the formation of granular Al 2 RE during solidification process of GW9411 alloy [16]. The lower cooling rate, the smaller the nucleation driving force of granular Al 2 RE [26].…”

“…In industrial production, gravity casting is an important way to prepare components with complex geometric dimensions. The grain size of casting alloys is quite coarse, and Zr is often used as a refiner [13,14], which is usually added in form of Mg-Zr intermediate alloy, but Zr refinement has the disadvantage of high cost and low utilisation [15,16]. These limit its extensive application.…”

Effect of Hot Rolling on the Microstructure and Mechanical Performance of a Mg-5Sn Alloy

“…Mg alloys are the lightest metallic structural materials with superior properties, such as excellent castability, good damping capacity, and high specific strength, making them ideal light-weight materials for applications in many industrial fields including automobiles and rail traffic [ 1 , 2 , 3 , 4 , 5 ]. It has been reported that every weight reduction of 100 Kg of a vehicle reduces the fuel consumption by 0.3–0.4 L/100 km [ 6 ].…”