中真空下制备具有优异力学性能的钛基非晶复合材料

In this paper, The Ti48Zr20Nb12Cu5Be15 bulk metallic glass composite were prepared by copper mould casting under medium vacuum conditions (0.15Pa-25Pa). The results demonstrated that the addition of impurity elements such us oxygen was neither induce the β-Ti →α-Ti phase transformation, nor change the microstructure of the Ti-BMG composites. Electron probe microanalysis (EPMA) measurements showed that oxygen was absorbed not only in the precipitated β-Ti phase, but also the BMGs. Oxygen concentration in the glass matrixes and crystalline phase are very close to each other, and both of them are increased with the average oxygen levels. The DSC curves give the evidence that the impurity elements concentrated in the BMGs will lead to a sharp decrease of glass forming ability while the average oxygen level above 4500ppm, which deteriorates the mechanical properties of BMGs. The impurity elements absorbed in the β-Ti phase can induce a significant solid-solution strengthening effect, which result in an enhanced strength and work-hardening behavior. The composites prepared under medium vacuum systems exhibit much better compressive yield strength than the composites prepared under high vacuum, while the compressive yield strength further increases from 1640 to 1770 MPa with the average oxygen level increases from 1700 to 2600 ppm. With the average oxygen level further increases, the ductility of the composites will decrease gradually.