冷却速度对快冷Ti合金组织与力学性能的影响

Influence of Cooling Speed on Microstructure and Mechanical Properties of Ti Alloys

通过铜模铸造法制备出了阶梯形的Ti66.7Ni20Cu13.3合金圆柱棒，直径分别为φ2mm、φ3mm、φ4mm和φ6mm。利用x射线衍射（XRD）仪和扫描电子显微镜（SEM）等研究了不同冷却速度对Ti66.7Ni20Cu13.3（原子百分比）合金组织与力学性能的影响。结果表明：合金形成Ti基非晶复合材料，直径为西3mm时塑性应变量最大为4．8％，直径为西4mm时最大强度达到1774MPa；随着直径的增大析出较多脆性相，导致试样破坏性脆断。

The alloys rods with diameters of 2 mm, 3 mm, 4 mm and 6 mm of Ti66.TNi20Cu13.3 were prepared by copper mold casting method. The influence of cooling speed on the microstructure and the mechanical properties of Ti66.7Ni20Cu13.3 （at%） alloys were investigated mainly by means of X-ray diffraction （XRD） and scanning electric microscopy （SEM）. It was shown that Ti-based amorphous composites were formed, the maximum plastic strain is 4.8% when its diameter is 43 mm; the maximum strength is 1 774 MPa when its diameter is 44 mm. The alloys precipitate brittle phase because of the increasing of the diameter, which cause the samples destructive fault by brittle fracture.