Rate and temperature dependent deformation behavior of as-cast WE43 magnesium-rare earth alloy manufactured by direct-chill casting

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:712

Article

Jahedi, Mohammad¹  McWilliams, Brandon A.²  Kellogg, Franklin R.³  Beyerlein, Irene J.⁴  Knezevic, Marko¹ 

[1] Univ New Hampshire, Dept Mech Engn, 33 Acad Way,Kingsbury Hall,W119, Durham, NH 03824 USA

[2] US Army, Weap & Mat Res Directorate, Res Lab, Aberdeen Proving Ground, MD 21005 USA

[3] SURVICE Engn Co, Belcamp, MD 21017 USA

[4] Univ Calif Santa Barbara, Dept Mat, Dept Mech Engn, Santa Barbara, CA 93106 USA

关键词: Rare earth magnesium alloys;    Crystallographic texture;    Deformation twinning;    Strain hardening;    Anisotropy;   

DOI  :  10.1016/j.msea.2017.11.092

来源: Elsevier

【 摘 要 】

In this work, we study the deformation behavior of a direct chill cast WE43 Mg alloy. This material initially has equiaxed grains approximately 40 gm in diameter and a random texture. The room temperature, quasi-static response exhibits little plastic anisotropy when evaluated parallel to and normal to the solidification direction and no initial yield tension-compression asymmetry. The deformation at room temperature is accompanied by significant basal texture development and formation of three types of deformation twins: {10 (1) over bar2}((1) over bar 011), {10 (1) over bar1}(10 (12) over bar), and {11 (2) over bar1}((1) over bar(1) over bar 26) as well as double twins {10 (1) over bar1}(10 (12) over bar)-{10 (1) over bar2}((1) over bar 011), although each in small amounts < 10% up to failure. We find that in the elevated 250 degrees C +/- 20 degrees C regime, the material exhibits a negative strain rate sensitivity, with a decreasing flow stress as the strain rate increases. In most of the high temperature, 250 degrees C to 350 degrees C, and high-strain-rate, 0.01/s to 10/s, tests, the material failed at moderate compression strains, 0.35-0.45. Subsequent fracture analyses find that the material fractures transgranularly by a typical shear fracture, often with the presence of additional arrested cracks. At elevated temperatures and under strain rates sufficiently low (i.e., 275 degrees C and 0.01/s, 300 degrees C and 0.1/s, 350 degrees C and 1/s, 375 degrees C and 10/s) or at a temperature of 400 degrees C deformation conditions, the material exhibited pseudo-super plastic behavior, experiencing relatively high deformation strains (> 1.0 true strain) without fracturing.

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