On the room temperature deformation mechanisms of a Mg-Y-Zn alloy with long-period-stacking-ordered structures
Abstract
We present a transmission electron microscopy study on the room temperature deformation mechanisms in a Mg97Y2Zn1 (at.%) alloy with long-period-stacking-order (LPSO) phase. The alloy consists of α-Mg matrix with platelet-shaped LPSO precipitates 3-5 nm thick and interdendritic LPSO (18R structures) phase grains. The interdendritic LPSO phase was found to deform either by kink-banding in conjunction with basal <a> slip or by basal <a> slip and the formation of dislocation walls. No orientation dependence of these different deformation modes was observed. The α-Mg matrix deforms by basal <a> slip and pyramidal <c + a> slip. No twinning was observed in the α-Mg matrix during room temperature deformation. The elastic modulus mismatch between α-Mg matrix and LPSO plates is suggested to be the main source for activating non-basal dislocations. The combination of the soft α-Mg matrix strengthened by LPSO precipitates and harder "bulk" interdendritic LPSO grains is suggested to contribute to the well-known good mechanical properties of Mg-LPSO alloys at room temperature.
- Publication:
-
Acta Materialia
- Pub Date:
- January 2015
- DOI:
- 10.1016/j.actamat.2014.09.036
- Bibcode:
- 2015AcMat..82..414K
- Keywords:
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- Magnesium alloy;
- Long-period-stacking-ordered structure;
- Dislocations;
- Deformation structures;
- Transmission electron microscopy