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采用机械球磨+放电等离子烧结的方法制备出高强度低模量的超细晶β型Ti28Nb2Zr8Sn合金。XRD和SEM结果表明,60 h球磨后的终态合金粉末经放电等离子烧结后,获得的超细晶块体合金为完全的bcc结构;TEM分析表明,超细晶块体合金中bcc结构的β-Ti晶粒为等轴状,其尺寸为500~1000 nm,远小于铸造法制备同类合金几十微米的晶粒尺寸;力学性能测试表明,随升温速率增大或保温时间缩短,超细晶块体合金的抗压缩强度逐渐增大,弹性模量逐渐减小。在烧结温度为900℃、升温速率为150℃/min且保温时间为0 min的条件下,得到的超细晶块体合金晶粒最细小,其压缩强度达到最大(2675 MPa),对应的断裂应变也最大(0.54),且其弹性模量最低(31.6 GPa);同时,该合金试样的加工硬化指数0.073远高于Ti6Al4V合金,这说明其加工硬化和塑性变形能力远远优于Ti-6Al-4V合金,故能够承受更大的载荷和经历更大的变形,可作为一种优异的生物医用候选材料。
The ultra-fine grain β-type Ti28Nb2Zr8Sn alloy with high strength and low modulus was prepared by mechanical ball milling and spark plasma sintering. XRD and SEM results show that the ultrafine-grained bulk alloy obtained after ball milling for 60 h is completely bcc structure after spark plasma sintering. The TEM analysis shows that the bcc structure β -Ti grains are equiaxed and have a size of 500-1000 nm, which is much smaller than that of several tens of micrometers in the same type of alloy prepared by the casting method. The mechanical properties tests show that as the heating rate is increased or the holding time is shortened, The compressive strength of the bulk alloy gradually increases, and the elastic modulus decreases gradually. Under the conditions of 900 ℃ sintering temperature, 150 ℃ / min heating rate and 0 min holding time, the grain size of the ultrafine-grained alloy is the smallest and its compressive strength reaches the maximum (2675 MPa). The corresponding fracture The strain is also the largest (0.54), and the lowest elastic modulus (31.6 GPa). At the same time, the work hardening index 0.073 of this alloy specimen is much higher than that of Ti6Al4V alloy, which shows that its work hardening and plastic deformation capacity far superior to Ti- 6Al-4V alloy, it can withstand greater load and experience greater deformation, can be used as an excellent bio-medical candidate material.