18R and 14H long-period stacking ordered structures in the Mg93.96Zn2Y4Sr0.04 alloy and the modification effect of Sr on X-phase

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 552; pp. 81 - 88
• Main Authors: Zhang, Jinshan, Chen, Changjiu, Que, Zhongping, Cheng, Weili, Xu, Jidong, Kang, Jingjing
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 30.08.2012; Elsevier
• Subjects: Alloy systems; Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Dissolution; Exact sciences and technology; Inorganic compounds; Long-period stacking ordered (LPSO) structure; Materials science; Mg–Y–Zn–Sr alloy; Microstructure; Modification; Physics; Stacking; Stacking faults; Stacking faults (SF); Stacking faults and other planar or extended defects; Strontium; Structural materials; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Modification; Stacking faults (SF); Long-period stacking ordered (LPSO) structure; Mg–Y–Zn–Sr alloy; Differential scanning calorimetry; Scanning electron microscopy; Stacking faults; Mg―Y―Zn―Sr alloy; Stacking sequence; Ductility; XRD; Casting; Solution heat treatment; Transmission electron microscopy; Microstructure; Grain refinement; Crystal structure
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2012.04.119

► Mg–Y–Zn alloy with LPSO structures was processed via conventional casting. ► Thickness of the X-phase decreased by addition of Sr. ► Simultaneous increase in both strength and ductility was obtained. ► 14H LPSO structure was generated in the α-Mg matrix when treated at 773K. The 18R and 14H long-period stacking ordered (LPSO) structures formed in the as-cast and solution-treated Mg93.96Zn2Y4Sr0.04 (at.%) alloys prepared by conventional permanent mold casting were investigated systematically by XRD, DSC, SEM and TEM. The examination of microstructure evolution revealed that part of the X-phase dissolved gradually into the α-Mg matrix and a fine plate-like phase with 14H LPSO structure was presented in the matrix during solution treatment at 773K for 35h. Furthermore, the refinement of X-phase and increment in the volume fraction of the lamellar regions in this phase could be discerned upon the addition of trace Sr (0.13wt.%) to the Mg94Zn2Y4 alloy. The improvement in ductility of the alloy could be ascribed to both the grain refinement and the appearance of stacking faults (SF) in the α-Mg matrix.