(1. 南昌航空大學 航空制造工程學院，南昌 330063；2. 上海交通大學 材料科學與工程學院，上海 200240)
摘 要: 研究試樣直徑和高徑比對3種鎂基塊體金屬玻璃Mg65Cu25Gd10、Mg65Cu20Ni5Gd10 和Mg75Ni10Gd10壓縮變形行為的影響，探討鎂基塊體金屬玻璃斷裂模式的轉變機制。壓縮應力—應變曲線和斷口掃描電鏡觀察結果表明：鎂基塊體金屬玻璃Mg65Cu25Gd10、Mg65Cu20Ni5Gd10 和Mg75Ni10Gd10在壓縮條件下可在3個不同的變形階段發(fā)生斷裂，第1個是彈性變形階段，在此變形階段金屬玻璃都以解理方式斷裂，無塑性；第2個變形階段的斷裂為解理和剪切混合方式斷裂，金屬玻璃具有一定的剪切塑性變形；第3個變形階段為穩(wěn)定剪切鋸齒塑性流變階段，在此變形階段金屬玻璃都是以剪切方式斷裂，具有穩(wěn)定的塑性變形；鎂基塊體金屬玻璃的斷裂模式與尺寸有關，減小試樣的直徑和高徑比都有利于塊體金屬玻璃由解理斷裂向剪切斷裂的轉變，強度和塑性也相應地得到提高。
關鍵字: 金屬玻璃；鎂合金；力學行為；尺寸效應
Mg-based bulk metallic glasses
（1. School of Aeronautical Manufacturing Engineering, Nanchang Hang Kong University, Nanchang 330063, China;
2. School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 330063, China）
Abstract:The effects of the as-cast diameter and aspect ratio on the compressive deformation behaviors of three Mg-based Mg65Cu25Gd10, Mg65Cu20Ni5Gd10 and Mg75Ni15Gd10 bulk metallic glasses (BMGs) were investigated. The mechanism for the transition of fracture modes of Mg-based BMGs was also discussed. The results from the stress—strain curves and fracture morphologies observed using scanning electron microscope (SEM) show that these Mg-based BMGs can fail at three different deformation stages under compression. The first stage is within the elastic regime, where the BMGs fail in a cleavage mode without plasticity. The second stage is in the range where the BMGs fail in the cleavage mode combining with the shear mode with a certain plastic deformation. The third stage means the serrated plastic deformation. In this stage, the BMGs fail in a pure shear mode after the obvious plastic serration. The fracture modes of these Mg-based BMGs are correlated with the sizes of the samples. Decreasing both the as-cast diameter and aspect ratio of the sample can favor the transition from the cleavage fracture to the shear fracture, resulting in higher strength and larger plasticity for the Mg-based BMGs.
Key words: metallic glasses; magnesium alloy; mechanical behaviors; size effect
