Dislocation Structure in Rapidly Solidified Mg<SUB>97</SUB>Zn<SUB>1</SUB>Y<SUB>2</SUB> Alloy with Long Period Stacking Order Phase

Abstract

Dislocation structure in rapidly solidified Mg 97 Zn 1 Y 2 ribbon with the long period stacking order (LPSO) phase is investigated by conventional transmission electron microscopy. In the grain with the LPSO phase there are no a dislocations lying on the basal plane, and a number of c þ a dislocations are visible. On the other hand, in the grain without the LPSO phase there are many straight a dislocations lying on the basal plane. These facts indicate that the critical resolved shear stress of the basal plane increases by the formation of the LPSO phase and the non-basal slip is activated by the prevention of the basal slip. In other words, the former directly contributes to the strengthening and the latter relates to the improvement of ductility with the increment of the number of the slip system. Therefore, it is concluded that the LPSO phase plays a unique role which overcomes the conflicting properties of strength and ductility in the mechanical property of the present alloy.

Cyclic Deformation Behavior of a Rare-Earth Containing Extruded Magnesium Alloy: Effect of Heat Treatment

“…In the RE-Mg alloys fine and evenly oriented (the planes parallel to the prismatic or basal planes of Mg matrix) and uniformly distributed particles can improve the tensile properties. [86] On the other hand, Yin et al [87] reported that relatively large size and small volume fraction of particles might have only small strengthening contributions. Thus, small sized particles or precipitates with an adequate volume fraction would have a significant contribution to the strengthening in RE-Mg alloys, as also reported in Reference 31.…”

Plastic deformation behavior of Mg12YZn with 18R long-period stacking ordered structure

“…Abe et al reported the peculiar chemical order of Y and Zn atoms in the Mg-based LPSO-phases, that is, the periodical enrichment of Y and Zn atoms at particular close-packed planes [5]. Although some models and ideas have been proposed to explain the strengthening mechanism of alloys containing the LPSO-phase on the basis of deformation substructure observations [9][10][11][12][13][14][15], the details have not yet been sufficiently clarified. This is because the plastic behavior of the LPSO-phase itself, especially the operative deformation mode, and its critical resolved shear stress (CRSS) have not been elucidated.…”

Effect of Rolling Temperature on the Microstructures and Mechanical Properties of Mg97Zn1Y2 Magnesium Alloy

“…Many aspects including Zn/Y ratio, precipitates, and grain refinement in Mg-Zn-Y alloys have been investigated ( . In contrast to this, less works have been done on the long period stacking order (LPSO) structure Z phase (Mg 12 ZnY) strengthening Mg-Zn-Y alloys, and most of them focused on the formation process of LPSO phase, dislocation structure, and variation of long period stacking order structure in rapidly solidified Mg 97 Zn 1 Y 2 alloy, since very recently a superior performance of rapidly solidified (RS) powder metallurgy Mg 97 Zn 1 Y 2 (at.%) alloy with extremely high tensile yield strength of 610 MPa and elongation of 5% has been developed and a yield strength more than 380 MPa at 200°C (Ref [11][12][13][14][15]. These excellent mechanical properties were archived by warm extrusion of gas-atomized Mg 97 Zn 1 Y 2 powders and were considered to be due to the hcp (2H)-Mg fine grain matrix of 100-200 nm in diameter with LPSO phase and the homogeneously dispersed M 24 Y 5 fine particles of less than 10 nm in diameter.…”