摘要
研究了近α型钛合金TG6经α+β两相区热加工的盘锻件在600℃长时暴露过程中的显微组织演变及其对热稳定性的影响。结果表明:经600℃/100h和600℃/300h长时高温暴露后,TG6钛合金的室温拉伸强度略有提高,其增幅在5%左右,而其拉伸塑性显著降低,塑性保持率小于50%,拉伸断口趋于平直化,且存在梯田状台阶和二次裂纹等,表现为显著的解理断裂特征。在600℃高温长时暴露过程中,TG6钛合金中的显微组织变化主要有在基体组织中的共格有序α2相析出及硅化物析出。随着高温暴露时间的延长,TG6钛合金的显微组织逐渐趋于稳定,拉伸性能的变化也相应趋缓。α2相析出促进了拉伸变形时位错滑移的平面化及变形不均匀,是热稳定性下降的主要原因;而硅化物析出协同促进位错滑移集中化,是热稳定性下降的次要因素。
Microstructural evolution of a near-α titanium alloy TG6 disc forging processed in α ＋ β phase field during long-term high tern-perature 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 microstruetural 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 nor reason for the ductility loss.
出处
《航空材料学报》
EI
CAS
CSCD
北大核心
2010年第1期11-18,共8页
Journal of Aeronautical Materials
关键词
显微组织演变
热稳定性
有序α2相
硅化物
断裂特征
microstructural evolution
thermal stability
ordered α2 phase
silicide
fracture characteristic
