Microstructure and mechanical properties of bulk Mg–Zn–Ca amorphous alloys and amorphous matrix composites

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• 作者：Qing-Feng Li ; Hui-Ru Weng ; Zhong-Yuan Suo ; Ying-Lei Ren ; Xiao-Guang Yuan ; Ke-Qiang Qiu
• 关键词：Mg– ; Zn– ; Ca alloys ; Amorphous matrix effect ; Glass forming ability ; Mechanical properties
• 刊名：Materials Science and Engineering ; A
• 出版年：2008
• 期刊代码：61_09215093
• 类别：ms
• 出版时间：25 July 2008
• 卷：487
• 期：1-2
• 页码：301-308
• 文件大小：2129 K

摘要

Samples with different diameters for Mg–Zn–Ca alloys were fabricated by copper mold casting method. The microstructure, amorphous nature and mechanical properties of as-cast samples were investigated by SEM, XRD and compressive tests. The results show that amorphous alloys or amorphous matrix composites can be formed in the composition of 1–6 at.%Ca for the samples with 2, 3 or 4 mm in diameters. During which the highest strength up to 828 MPa and plastic deformation of 1.28%were obtained for Mg₆₈Zn₂₈Ca₄ alloy with a monolithic amorphous structure. The best composition range defined both by strength and plastic deformation should be 3–5 at.%Ca for Mg_72−xZn₂₈Ca_x (x = 0–6) alloys. At least over 400 MPa of fracture strength was obtained for the samples with an amorphous matrix, indicating that Mg–Zn–Ca alloys can be good candidates for amorphous matrix composites fabrication. In order to further consider the amorphous matrix effect on mechanical properties, Mg_95−xZn_xCa₅ (x = 15–33) alloys were investigated by the same methods. Mg₈₀Zn₁₅Ca₅ alloy with no obviously amorphous structure exhibits a lower yielding strength of 307 MPa but it shows excellent plastic strain over 3.5%. We suggest that the amorphous matrix can enhance both the yielding strength and fracture strength of magnesium alloys.