用TEM,SEM,X射线衍射及拉伸试验等研究了47121β-Ti合金的拉伸性能与α相形貌及其断裂行为的关系。结果表明,低温时效由ω相转变成的弥散α相质点,随其体积分数增加,质点间共格应力场发生交叠,产生较强的内应力,在负荷作用下,导致宏观脆断,而微观断裂机制仍属于韧窝,因此可以把局部的内应力区认为是形成精细韧窝的核心。魏氏组织的α相具有强的加工硬化效应,位错切割α相是主要强化机制,但以孪生形变的α相片阻止位错切过。晶界两侧形成的无析出带,以及随后形成的羽毛状α相群,都使晶界区弱化,导致形成类似沿晶型断口。
An investigation was conducted to examine the tensile property of 47121 β-Ti alloy in relation to the morphology of α-phase and to the fracture behaviour by means of TEM, SEM and X-ray diffraction as well as tension test. The results showed that with the increasing of volume fraction of the dispersive α-phase particles, transformed from ω-phase in situ during its aging at low temperature, the coherent stress field between particles overlapped each other and the stronger internal stress field formed in the specimen. Under the action of loading the macroscopic brittle fracture followed but on the microscopic fracture mechanism it fractured really into dimples. Therefore, the local internal stress peaks may be considered as the nuclei to form the fine dimples. The α-phase of Widmans(?)tt structure has much effect on the work-hardening. Cutting through the α-phase particles by dislocation seems to be the main strengthening mechanism in this condition, but the particles of deformation-twinned α-phase obstruct the cutting by dislocation. The non-precipitated zone formed nearby the both sides of grain boundaries together with the colony of further grown feather-like α-phase might weaken the grain boundary zone and lead it to form an alike intergranular fracture on the broken specimen.
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