Investigation of texture, microstructure, and mechanical properties of a magnesium–lanthanum alloy after thermo-mechanical processing

Abstract

The texture, microstructure, and mechanical properties of Mg-1.33La (wt.%) alloy after hot rolling and cold plane strain compression were investigated by using X-ray diffraction, optical microscopy, and micro-hardness measurements. This thermo-mechanical processing resulted in a relative weakening of the texture that was mainly a basal type. The microstructures after hot rolling and cold plane strain compression revealed the presence of a second phase (Mg17La2), mostly at grain boundaries. Twins were profuse, and their morphologies were quite different after hot rolling and cold plane strain compression. The Mg-1.33La (wt.%) alloy exhibited good room temperature formability and an increase in strength. The alloy's hardness increased with increasing deformation strain. Such properties were explained by the effect of both the Mg17La2 phase precipitation and the sample's texture.

Texture and microhardness of Mg-Rare Earth (Nd and Ce) alloys processed by high-pressure torsion

“…To the present time, little information is available on the crystallographic texture and mechanical properties of Mg-RE alloys subjected to HPT processing [33] and this contrasts with the extensive published data about Mg-based alloys subjected to conventional deformation [40][41][42][43][44][45]. Accordingly, the objective of the present research was to investigate the influence of HPT processing at room temperature on the texture and the microhardness of two Mg-RE alloys (Mg-1.43Nd and Mg-1.44Ce (wt.…”

The deformation and recrystallization behaviour of an Mg-Dy alloy processed by plane strain compression

“…First, the stress shows a rapid increases due to the strain hardening to reach a maximum of 225 MPa at ε = -0.32 and decreases up ε = -0.6 to increases again. This secondary strain hardening (at ε ~ -0.6) is present in all processed samples (Figure 2) and it is usually seen in PSC processed Mg-based alloys and result from the result of the friction between the sample and channel-die [12,14,29,30].…”

“…Thermo-mechanical processing and alloying elements have proven their efficiency to improve the formability and reduce the mechanical anisotropy of Mg-based alloy, especially by microstructural modifications. Hot deformation allows the activation of prismatic and pyramidal <c+a> slip systems and the occurrence of dynamic recrystallization (DRX) which improves the mechanical properties of Mg-based alloys by grain refinement [6][7][8][9][10][11][12][13][14]. Several mechanisms regrouped in two categories: discontinuous DRX (DDRX) and continuous DRX (CDRX) mechanisms have been proposed to explain the effect of DRX on the performance of Mg-based alloys.…”

An investigation by EXAFS of local atomic structure in an Mg-Nd alloy after processing by high-pressure torsion and ageing

“…Magnesium and its alloys are interesting materials for lightweight structural applications [1].Nevertheless, these alloys exhibit in sufficient low temperature formability due to their limited slip systems 2 and this serves to restrict their use for industrial applications [2]. In practice, small amounts of additions of rareearth (RE) elements can improve the mechanical properties such as the ductility of Mg-based alloys [3]. In addition, the application of severe plastic deformation (SPD) processing, as in high-pressure torsion (HPT), has been used to achieve good mechanical properties through grain refinement and the introduction of high dislocation densities [4].…”

“…shows the experimental and best fit k3 -weighted EXAFS spectra at the Nd LIII-edge for all samples and their corresponding Fourier Transform magnitudes, respectively. The structural parameters including the atomic bond, number of atoms, bond length and the Debye-Waller factor obtained from these fits are summarized inTable 1.The Fourier Transform magnitudes of the EXAFS signal of the un-aged and aged samples show four peaks.…”