高强韧Mo-0.1Zr合金的制备、性能及组织

Preparation,performance and structure of high tenacious Mo-0.1Zr alloy

采用球磨制备Mo-0.1Zr粉末,经压制成型、预烧、高温烧结和真空热处理后,制备抗拉强度超过650 MPa、伸长率大于30%的高强韧Mo-0.1Zr合金,研究真空热处理对合金性能与显微组织的影响。结果表明:经高温烧结后,Mo-0.1Zr合金与纯Mo相比性能提高不明显,断口形貌呈明显的沿晶脆性断裂特征;但经真空热处理后,Mo-0.1Zr合金的性能显著提高,抗拉强度提高了40%、伸长率从7.3%提高到31.2%,合金断口也由沿晶脆性断裂转变为穿晶韧性断裂,且部分晶粒呈韧性撕裂特征。真空热处理温度对合金性能的影响很大,真空热处理温度过高容易使晶粒长大,导致性能提高程度下降;而真空热处理温度过低难以起到消除晶体缺陷的作用,对合金性能提高有限。

Mo-0.1Zr powder was prepared by ball-milling,then this powder was made into high tenacious alloy with tensile strength above 650 MPa and elongation above 30% after a series of processes including press forming,pre-sintering,high-temperature sintering,and vacuum heat treating.The effects of vacuum heat treatment on properties and microscopic structure of the alloy were investigated.The results show that,after sintering at high temperature,the properties of Mo-0.1Zr alloy have no obvious improvement compared with pure Mo,and its fracture exhibits an obvious characteristic of intergranular brittle rupture.However,after vacuum heat treatment,the performance of Mo-0.1Zr alloy rises obviously,tensile strength increases by 40%,elongation percentage increases from 7.3% to 31.2%,and alloy fracture translates from intergranular brittle rupture to transcytalline ductile rupture.At the same time,parts of the grains exhibit a characteristic of ductile tearing.The significant increase in performance of Mo-0.1Zr alloy after vacuum heat treatment is closely related to the elimination of vacancies and dislocations.However,an excessively high temperature will cause the grain growth,resulting in the decrease of increasing extent of alloy performance;an excessively low vacuum heat treatment temperature has little effect on increasing the alloy performance because it can hardly play a role in eliminating crystal defects.