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

Abstract

The influence of high-pressure torsion (HPT) processing on the texture and microhardness of two binary Mg-RE (RE=Nd and Ce) alloys was investigated using X-ray diffraction and Vickers microhardness measurements. Disks cut from the alloys were processed by HPT at room temperature for up to 10 turns. The precipitation products of both alloys were identified using synchrotron radiation. The results show that both alloys exhibit a weak basal texture where the c-axis of most grains is shifted 15° from the shear direction. An Mg-1.44Ce (wt. %) alloy showed a continuous decrease in the texture strength which may be due to the effect of second precipitation phases (Mg 17 Ce 2 and MgCe 2). The microhardness of both alloys increased significantly with increasing HPT turns but levelled-off beyond about one HPT turn. Maximum values of ~65 and ~96 Hv were achieved which are significantly higher than the hardness of the undeformed Mg-Ce and Mg-Nd alloys.

An investigation of the thermal stability of an Mg Dy alloy after processing by high-pressure torsion

“…The evolution of the deformation texture in the present work is different from earlier reports for pure Mg [51] or Mg-RE alloys [52] processed by HPT at room temperature.…”

“…planes are parallel to the shear (SD, RD) plane [51] while the textures of Mg-RE (RE=Nd, Ce) alloys after HPT processing are characterized by an asymmetric basal texture shifted by 15° towards the shear direction [52]. The texture of the as-cast Mg-0.41Dy alloy was…”

Evaluating the textural and mechanical properties of an Mg-Dy alloy processed by high-pressure torsion

“…The tilted texture of 15° towards the SD observed in the middle and edge of the HPT samples is due to the activation of other deformation modes such as prismatic slip on <a>{101 ത 0}<1 ത 21 ത 0> and/or pyramidal slip on <c+a> {112 ത 2}<112 ത 3> [44]. The weaker basal texture developed in the present alloy, or in Mg-RE (RE = Nd, Ce alloys [35]) in general relative to the AZ31 Mg alloy [14], is explained by the effect of RE elements in promoting the <a> prismatic and <c+a> pyramidal slip systems. This effect is attributed to the decrease in stacking fault energy and the reduction in dislocation motion and the ability to cross slip as the solutes diffuse in the dislocation cores 15 HPT turns.…”

“…Therefore, the hardening mechanism in the 1/2 turn disc does not follow the same trend since the difference between the experimental and calculated values is close to ~13.5 Hv. In practice, texture strengthening is considered to play an important role in the rapid hardening in the early stage of deformation [35,62]. Thus, as can…”

Processing Magnesium and Its Alloys by High‐Pressure Torsion: An Overview

“…The as‐received material exhibits an [hki0] fiber and but this changes to a [0001] fiber with the c ‐axis parallel to the torsion axis after 1 turn of HPT and further processing to 5 turns leads to no significant additional change. A basal texture with a slight rotation toward the shear direction was observed in Mg‐1.43% Nd and Mg‐1.44% Ce alloys processed by HPT …”