Microstructure and mechanical properties of Mg-Cu-Y-Zn bulk metallic glass matrix composites prepared in low vacuum
(1. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China;2. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University,Qinhuangdao 066004, China)
Abstract: Mg-Cu-Y-Zn bulk metallic glasses (BMG) and in situ bulk metallic glass matrix composites were prepared by copper mold casting under the low vacuum with the argon atmosphere, and the raw materials used in preparing the Mg-Cu-Y-Zn alloys were commercially pure materials. The microstructures of the bulk samples were analyzed by X-ray diffractometer (XRD) and the thermal stability of samples was investigated by using a differential scanning calorimeter (DSC). The thermal stability of sample prepared with commercially pure raw materials is close to that of sample prepared with the high pure raw materials for the BMG Mg65+X(Cu0.66Y0.33)30-XZn5 (X=6). With the increase of Mg content, Mg-Cu-Y-Zn composites are prepared, in which Mg solid solution flakes and Y2O3 flakes are dispersed. In comparison with monolithic Mg-based BMG alloys, the composites exhibit significant improvement in mechanical properties, e.g. a compressive plastic strain about 7% and an ultimate strength of 1 170 MPa in Mg65+X(Cu0.66Y0.33)30-XZn5 (X=14). It is suggested that the enhancement of the mechanical properties of the composites can be attributed to the generation of multiple shear bands and the quantity of the Mg solid solution flakes.
Key words: bulk amorphous alloys; magnesium; commercially pure raw materials; microstructure; mechanical property