等径角挤压制备超细生物医用纯钛的静态力学性能和塑性

摘要

等径角挤压是制备超细晶和纳米晶材料最有效的工艺之一.由于工业纯钛具有极佳的生物相容性,因此它可用作生物植入体材料.然而,较低的静/动态强度是纯钛类材料的不足之处.利用等径角挤压工艺可消除此类缺陷.本文作者在室温和通道角为135°条件下进行3道次挤压得到2级工业纯钛试样(2级CP-Ti).对经等径角挤压3道次的CP-Ti样品进行显微组织分析及拉伸、硬度、三点弯曲和夏比冲击等力学性能测试.样品的显微组织演变结果表明,经等径角挤压工艺后样品的粗晶组织转变成超细晶或纳米晶组织.此外,力学性能测试结果表明,等径角挤压工艺能显著提高工业纯钛的屈服强度、抗拉强度、弯曲强度、硬度和断裂韧度,因此用该工艺制得的钛可以作为金属合金的替代品用作生物医用材料.%Equal channel angular pressing (ECAP) is one of the most effective processes to produce ultra-fine grain (UFG) and nanocrystalline (NC) materials. Because the commercially pure titanium exhibits excellent biocompatibility properties, it has a significant potential to be utilized as an implant material. The low static and dynamic strengths of the pure titanium are one of the weaknesses of this material. This defect can be removed by applying the ECAP process on the pure titanium. In this work, the commercially pure titanium Grade 2 (CP-Ti of Grade 2) was pressed at room temperature by the ECAP process via a channel angle of 135° for 3 passes. The microstructural analysis and mechanical tests such as tensile test, hardness test, three-point bending test and Charpy impact test were all carried out on the ECAPed CP-Ti through 3 passes. The microstructural evolution reveals that by applying the ECAP process, coarse grain (CG) structure develops to UFG/NC structure. Moreover, the results of the mechanical tests show that the process significantly increases the yield and ultimate tensile strengths, bending strength, hardness and fracture toughness of the commercially pure titanium so that it can be used as a replacement for metallic alloys used as biomaterials.