Evaluating the flow properties of a magnesium ZK60 alloy processed by high-pressure torsion: A comparison of two different miniature testing techniques

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

卷:708

Article

Torbati-Sarraf, Seyed Alireza^1,2  Alizadeh, Reza³  Mahmudi, Reza³  Langdon, Terence G.⁴ 

[1] Univ Southern Calif, Dept Aerosp & Mech Engn, Los Angeles, CA 90089 USA

[2] Univ Southern Calif, Dept Mat Sci, Los Angeles, CA 90089 USA

[3] Univ Tehran, Sch Met & Mat Engn, Coll Engn, Tehran, Iran

[4] Univ Southampton, Mat Res Grp, Fac Engn & Environm, Southampton SO17 1BJ, Hants, England

关键词: High-pressure torsion;    Superplasticity;    Strain rate sensitivity;    Shear punch testing;    Ultrafine-grained material;   

DOI  :  10.1016/j.msea.2017.10.009

来源: Elsevier

【 摘 要 】

A ZK60 magnesium alloy was processed through 5 turns of high-pressure torsion (HPT) at room temperature under an applied pressure of 2.0 GPa to produce a reasonably homogeneous ultrafine microstructure with a grain size of similar to 700 nm. The potential superplastic behavior of this alloy was investigated by measuring the strain rate sensitivity using two different procedures of miniature tensile testing and miniature shear punch testing (SPT). The tensile experiments were conducted at initial strain rates of 3.0 x 10(-5) to 1.0 x 10(-1) s(-1) and the SPT was performed at shear strain rates from 3.3 x 10(-3) to 3.3 x 10(-1) s(-1) at temperatures of 473 and 523 K. It is shown that the strain rate sensitivity index, In, has a maximum value of similar to 0.5 at intermediate strain rates in both tensile testing and SPT and there was a maximum elongation to failure of 940% in the tensile testing. The results demonstrate that tensile testing and SPT are both effective procedures in indicating the potential for achieving superplasticity.

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