Influence of Yttrium Addition on Plastic Deformation of Magnesium

Abstract

Tensile tests of single crystalline and polycrystalline Mg-Y alloys were carried out at room temperature to investigate the in uence of yttrium on activation of <c+a> slip systems and to clarify the relationship between ductility of magnesium and the activation of <c+a> slip systems. Tensile directions of single crystals and polycrystals were parallel to (0001) and their rolling direction, respectively. Mg-(0.6-1.1)at%Y alloy single crystals yielded due to the rst order pyramidal <c+a> slip (FPCS). Yield stress and ductility of Mg-(0.6-1.1)at%Y alloy single crystals were higher than those of pure magnesium. Mg-0.9at%Y alloy polycrystals showed higher ductility than pure magnesium. The number of grains where second order pyramidal slips were activated was the largest in those where non-basal slips were activated in pure magnesium, while those where FPCS were activated increased with increasing strain in Mg-0.9at%Y alloy. High ductility of Mg-0.9at%Y alloy would be caused by activation of FPCS due to yttrium addition.

Roles of Slip and Twinning on Indentation Formations in Magnesium Alloy Single Crystals

“…2 and 3, indentation morphology changed from elliptic to circular with increasing yttrium content, revealing the change in slip degree. Rikihisa et al 14) applied MgY alloy single crystals with different yttrium contents to tensile tests and reported that not only SPCS but also first order pyramidal ©c + aª slip (FPCS) were activated and that CRSS for FPCS increased by yttrium addition. Therefore, the difference between morphologies in 05Y and 09Y indentations would be caused by the difference in the activation of FPCS.…”

“…CRSSs for basal slip and second order pyramidal ©c + aª slip (SPCS) have been reported to change when aluminum, 911) zinc 12,13) and yttrium 13,14) are added to magnesium. Also, the loading direction to cause f10 12g twins, a typical deformation twin of HCP metals, is known to depend on c/a; the critical value is ffiffi ffi 3 p…”

Effects of Yttrium Addition on Plastic Deformation of Rolled Magnesium

“…Four, one, and three specimens were prepared for Mg0.54 at% Y (0.5Y), Mg0.9 at% Y (0.9Y), and Mg1.21 at% Y (1.2Y), respectively. Data of pure magnesium (Mg) and Mg0.9 at% Y alloy (0.9Y-2) 7) were used for comparison. 0.9Y-2 was also produced by casting, rolled and annealing.…”

“…0.9Y-2 was also produced by casting, rolled and annealing. 7) Specimens were mechanically polished using emery paper (# 400-4000), an MD-Nap (Struers), and diamond spray 1 mm (Struers). Specimen surfaces after mechanical polishing were chemically polished to mirror using a polishing cloth soaked in a solution (HNO 3 :H 2 O 2 :C 2 H 5 OH = 5:7:20).…”

“…As trace analysis can distinguish which FPCS and SPCS slip systems caused ©c + aª slip, the effects of active slip systems on mechanical properties can be investigated. Using trace analysis, Rikihisa et al 7) performed tensile tests of MgY alloy single crystals and polycrystals and reported the effect of yttrium addition on pyramidal slips of magnesium. MgY alloy single crystals yielded due to FPCS when yttrium addition was in the range of 0.61.1 at% while yielding due to f10 10gh11 20i prismatic slip (PS) when yttrium addition exceeded 1.1 at%.…”