Microstructural Evolution of Near-α Titanium Alloy during Long-Term High Temperature Exposure and its Influence on Thermal Stability

CAI Jian-ming; HUANG Xu; CAO Chun-xiao; MA Ji-min

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Journal of Aeronautical Materials ›› 2010, Vol. 30 ›› Issue (1) : 11-18.

Microstructural Evolution of Near-α Titanium Alloy during Long-Term High Temperature Exposure and its Influence on Thermal Stability

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Abstract

Microstructural evolution of a near-α titanium alloy TG6 disc forging processed in α+β phase field during long-term high temperature exposure and its influence on the thermal stability were studied.The results show that the room temperature tensile strength increased about 5% and the ductility reduced remarkably lower than 50% after 600℃/100h or 300h exposed for TG6 titanium alloy,and the fracture surface has a tendency of flat,terrace-like steps and secondary crack which showed an obvious cleavage fracture characteristic.During long-term exposure under 600℃ environment,the microstructural change is precipitation of the coherent ordered α2 phase and silicide.The microstructure and the tensile properties tend to be stable with increasing the exposure time.The precipitation of α2 phase is the main reason for the great loss of ductility during high temperature long-term exposure because the precipitated α2 may promote planar slip and inhomogeneous deformation while tensile deformation.The precipitation of silicide may promote the intensity of slip and is the minor reason for the ductility loss.

Key words

microstructural evol / thermal stability / ordered α2 phase / silicide / fracture characteris

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CAI Jian-ming, HUANG Xu, CAO Chun-xiao, MA Ji-min. Microstructural Evolution of Near-α Titanium Alloy during Long-Term High Temperature Exposure and its Influence on Thermal Stability[J]. Journal of Aeronautical Materials, 2010, 30(1): 11-18

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