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本文对一种新型亚稳β型Ti-30Nb-1Mo-4Sn(%,质量分数)合金时效过程中ω相与α相的竞争行为进行了系统研究。研究表明,Ti-30Nb-1Mo-4Sn合金经固溶处理或冷轧处理后,合金的相组成均为β相和α“马氏体。有趣的是,固溶态和冷轧态Ti-30Nb-1Mo-4Sn合金经相同的时效处理(即573K时效2h)后,析出产物分别为等温ω相和α相。这主要是由于冷轧后合金内部含有大量位错和晶界,这些位错和晶界在后续时效过程中抑制了等温ω相的析出,同时为α相的异质形核提供了条件,促进了α相的析出。这一发现为亚稳β钛合金时效过程中ω相与α相之间的竞争提供了直接的证据。此外,上述研究结果也清楚地表明,通过对亚稳β钛合金进行冷轧预处理,可以在后续时效过程中抑制脆性ω相析出的同时在合金中获得对力学性能有利的细小α强化相,这无疑对研发低模量和高强度兼备的新型β钛合金具有重要的意义。
In this paper, the competitive behavior of ω phase and α phase in a new type of metastable β-Ti-30Nb-1Mo-4Sn (%, mass fraction) alloy has been studied systematically. The results show that the phases of Ti-30Nb-1Mo-4Sn alloy are β-phase and α ”martensite after solution treatment or cold-rolling treatment.It is interesting that the solid solution and cold-rolled Ti- After the same aging treatment (ie, aging at 573K for 2h), the precipitated products of 30Nb-1Mo-4Sn alloy are isothermal ω phase and α phase, respectively, mainly due to the large amount of dislocations and grain boundaries in the alloy after cold-rolling, And grain boundary in the subsequent aging process inhibited the precipitation of isothermal ω phase, at the same time for the α phase heterogeneous nucleation provides the conditions to promote the precipitation of α phase.The discovery of metastable β titanium alloy aging phase ω And α phase provide direct evidence of competition.In addition, the above results also clearly show that by metastable β titanium alloy cold-rolled pre-treatment, can be suppressed in the subsequent aging brittle ω-phase precipitation at the same time Alloy obtained in the favorable mechanical properties of fine α-enhanced phase, which undoubtedly research and development of low modulus and high strength of the new beta titanium alloy is of great significance.