Twin-assisted precipitation during hot compression of an Mg-Gd-Zn-Zr magnesium alloy

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

卷:706

Article

Saadati, Mohammad¹  Khosroshahi, Rasoul Azari¹  Ebrahimi, Golamreza²  Jahazi, Mohammad³ 

[1] Sahand Univ Technol, Fac Mat Engn, Tabriz, Iran

[2] Hakim Sabzevari Univ, Fac Engn, Mat & Polymers Engn Dept, Sabzevar, Iran

[3] Ecole Technol Super, Dept Genie Mecan, 1100 Notre Dame St West, Montreal, PQ H3C 1K3, Canada

关键词: Twin-assisted precipitation;    Hot compression;    Precipitate morphology;    Schmid factor;    LPSO structure;   

DOI  :  10.1016/j.msea.2017.08.112

来源: Elsevier

【 摘 要 】

Dynamic precipitation in an Mg-Gd-Zn-Zr alloy during hot compression at 350 degrees C and 450 degrees C and at strain rates of 0.001-0.1 s(-1) is investigated. The deformation conditions were designed such as to promote twinning or slip of dislocations. The results indicated that both twinned and non-twinned grains were present at 350 degrees C, with the extent being a function of the applied strain rate. The formation and propagation of {10 (1) over bar2}((1) over bar 011) primary tensile twins within the twinned grains was identified as being at root of the twin-assisted precipitation phenomenon. The precipitates had spherical-morphology in the twinned grains whereas parallel arrays of rod-shaped precipitates formed in the non-twinned grains due to dynamic precipitation on the slip bands and the stacking faults. Twin assisted precipitates were suppressed by increases in the strain rate at 350 degrees C because of the shorter time required for solute element diffusion towards the nucleated precipitates at that temperature. Increasing the deformation temperature to 450 degrees C changed the dominant deformation mechanism from twinning to slip of dislocations, resulting in the formation of rod-shaped precipitates similar to those observed in non-twinned grains at 350 degrees C. An EBSD analysis was used to study the dominant deformation mechanism as a function of the Schmid factor, and the twinning deformation mechanism was found to be predominant in the grains having a lower Schmid factor.

【 授权许可】

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