【摘要】 采用铜模铸造法制备了直径分别为2、3、5mm的Mg₇₅Ni₁₂Zn₅Y₈合金试样,分别采用X射线衍射仪（X-ray diffraction,XRD）、扫描电子显微镜（scanning electron microscopy,SEM）和力学性能试验机对试样进行测试,研究冷却速度对合金组织结构与力学性能的影响。结果表明,2mm试样主要为非晶结构,3mm和5mm试样的非晶基体中析出α-Mg、Mg₁₂YZn、Mg₂Ni等晶态相。随着试样直径的增加,非晶基体中晶态相的种类、含量和尺寸均改变。2 mm和3 mm试样的压缩断裂强度分别为772 MPa和702MPa,3mm试样的塑性应变达到3.98%。2mm和5mm试样的断口表现出脆性断裂特征,3mm试样的断口具有典型的非晶复合材料不连续脉状纹断裂特征。更多还原

【Abstract】 Mg₇₅Ni₁₂Zn₅Y₈ alloy samples with 2,3,5 mm in diameter were fabricated by Cu-mold casting method.The X-ray diffraction（XRD）,scanning electron microscopy（SEM）and mechanical property testing were used to investigate the effects of cooling rate on the microstructure and mechanical properties of the alloys.The results show that the sample with 2 mm in diameter exhibits mainly amorphous structure.For the samples with 3 mm and 5 mm in diameter,theα-Mg,Mg₁₂YZn and Mg₂Ni phases were precipitated from the amorphous matrix.With the increase of the diameters of the sample size,the type,content and size of the crystalline phases in the amorphous matrix were also changed.The compressive fracture strength of the 2 mm and 3 mm samples are 772 MPa and 702 MPa respectively,and the plastic strain of the 3 mm sample reached 3.98%.The fracture surface of the samples with 2 mm and 5 mm in diameter are brittle,while the fracture surface of the sample with 3 mm in diameter is typical amorphous matrix composites nature in term of discontinuous vein pattern.更多还原