块体非晶合金Cu_(58)Zr_(20)Ti_(20)Mo_2的形成与力学性能

Formation and mechanical properties of Cu_(58)Zr_(20)Ti_(20)Mo_2 bulk metallic glass

用铜模吸铸法获得直径3 mm的Cu58Zr20Ti20Mo2块体非晶合金,采用X射线衍射仪、示差扫描量热仪、压缩实验及扫描电镜等研究其结构、热稳定性、压缩性能及断口形貌。Mo的引入有利于非晶的形成,该非晶合金表现为两级晶化行为,玻璃转变温度为422.6℃,晶化起始温度为453.4℃;其压缩应力—应变曲线呈近似线性关系,不存在塑性变形阶段,为脆性断裂,断裂强度为1 720 MPa,变形量为3.4%,断口形貌为清晰的脉状河流花纹;含少量晶态相的Cu57Zr20Ti20Mo3非晶合金仍为脆性断裂,断裂强度为1 546 MPa,变形量为3.3%,断口形貌呈混乱的脉状河流花纹,且有类似液滴的小球形貌。

Bulk metallic glass （BMG） Cu58Zr20Ti20Mo2 rods with a diameter of 3 mm were prepared by using copper mould suction cast. The structure, thermal stability, compression strength and fracture morphology of this bulk metallic glass were investigated by X-ray diffractometry, differential scanning calorimetry, compression tester and scanning electronic microscopy. The results indicate that a small addition of molybdenum is beneficial for improving glass-forming ability in Cu60Zr20Ti20 system. This amorphous alloy shows a two-stage crystallization, the glass-transition temperature is about 422.6℃ and the onset of crystallization temperature is 453.4 ℃. Moreover, this amorphous alloy exhibits a linear relation between the stress and strain and shows a brittle fracture mode. The compression strength is about 1 720 MPa and the elongation about 3.4%. The surface morphology of fracture shows a clear vein pattern. The characteristics of both compression behaviour and fracture of Cu57Zr20Ti20Mo3 alloy with a small amount of amorphous phase are similar to those of the above fully amorphous alloy, but the strength deer eases to 1 546 MPa, the elongation is 3.4% and the vein pattern becomes a little disordered and some liquid drops can be observed in the fracture surface.