(沈阳铸造研究所,沈阳 110022)
摘 要: 通过熔配5种成分(w(Nb)=15%,20%,25%,30%,35%)的钛铌合金,采用石墨铸型浇注成棒状试样,并进行固溶处理,研究铌元素对铸造纯钛组织和性能的影响。结果表明:铌可以显著降低铸造纯钛的硬度、弹性模量和线膨胀系数,并提高强度。在铌含量为15%~35%范围内,Ti-20%Nb合金具有最低的硬度(HRC=5)和最低的弹性模量(E=56 GPa);当铌含量约为25%时合金具有最小的平均线膨胀系数( =6.6×10-6/℃(20~100 ℃))。固溶后合金抗拉强度为520~660 MPa,伸长率为19%~32%。TN系列合金固溶组织由基体相β和针状析出相α″、α′和α相组成,α″和β相是造成铸造纯钛硬度、弹性模量和线膨胀系数降低的主要原因。
关键字: 铌元素;钛合金;硬度;弹性模量;线膨胀系数
(Shenyang Research Institute of Foundry, Shenyang 110022, China)
Abstract:Five kinds of Ti-Nb alloys (w(Nb)=15%, 20%, 25%, 30%, 35%) were prepared, melted into rod with graphite mould, and solution-treated to investigate the effect of single Nb addition on the microstructure and properties of cast pure titanium. The results shows that Nb element can significantly decrease the hardness, elastic modulus and linear expansion coefficient, and increase the strength of cast pure titanium. In the Nb mass frachion range of 15%~35% the Ti-20% Nb alloy has the lowest Rockwell hardness (HRC=5) and the lowest elastic modulus (E=56 GPa); and the Ti-25% Nb alloy has the lowest linear expansion coefficient ( =6.6×10-6/℃, 20~100 ℃). The tensile strength and elongation of the Ti-Nb alloys are in the ranges of 520~660 MPa and 19%~32%, respectively. The microstructures of the solution-treated Ti-Nb alloys all are composed of matrix β-phase and acicular precipitated phases α′ and α″ and phase α. Phase α″ and β-phase are the main reasons of low Rockwell hardness, low elastic modulus and low linear expansion coefficient for the Ti-Nb alloys.
Key words: element Nb; titanium alloy; hardness; elastic modulus; linear expansion coefficient