材料期刊网

利用X射线衍射仪(XRD)、光学显微镜、万能试验机和扫描电镜(SEM)等仪器研究在不同热处理温度下的Zr48 Co52合金的微观组织和力学性能.结果表明,合金在723 K和773 K温度下进行热处理后的相组成和铸态合金相组成相同,主要相仍为简单立方结构的B2相,在基体B2相上析出少量的B33相.另外,铸态合金和在热处理温度为723 K和773 K时,合金的微观组织形貌呈现“麦穗”状、长条状和颗粒状等轴晶,且等轴晶尺寸为2～4 μm.在热处理温度为773 K,合金的最大抗压强度为848 MPa,而断裂强度为825 MPa,维氏硬度为396 HV.在对断口进行分析,发现以铸态合金延性断裂为主的断裂机制转变为在723 K和773 K下进行热处理的以沿晶断裂和解理断裂为主,延性断裂为辅的断裂机制.

Effects of heat treatment temperature on microstructure and mechanical properties of Zr48 Cos2 alloy were studied by means of X-ray diffraction (XRD),metallographic microscope,universal testing machine and scanning electron microscopy (SEM).The results show that under the heat treatment temperature of 723 K and 773 K,the phase composition of the alloy is the same as that of the as-cast alloy.The main phase is still a simple cubic structure of B2 phase,and a small amount of B33 phase is precipitated in the B2 matrix phase.In addition,the microstructure of the as-cast alloy and the heat-treatment alloys in the temperature of 723 K and 773 K are the "wheat" shape,the strip and equiaxed grains,and the sizes of the equiaxed grains are 2-4 μm.The maximum compressive strength of the alloy with the heattreatment temperature of 773 K is 848 MPa,and the fracture strength is 825 MPa,and the Vickers hardness is 396 HV.The fracture analysis shows that the fracture mechanism of the as-cast alloy is main ductile fracture,however,the fracture mechanism of the alloys with the the heat-treatment temperature of 723 K and 773 K are the intergranular fracture and cleavage fracture,and the subsidiary ductile fracture.