论文部分内容阅读
利用金相显微镜、扫描和透射电镜等仪器表征了TiAl合金的片层组织及结构特征,研究了Ti-48Al at%合金片层组织的形成机制和片层组织细化工艺及其机理。结果表明,Ti-48Al合金单级热处理能够得到全片层组织,平均晶粒尺寸约150μm,片层间距约1.30μm。其形成过程是:γ相在α相晶内(0001)面上通过全位错分解成核,通过不全位错滑移、层错区扩展而长大。循环热处理和双温热处理均能将片层晶粒尺寸细化到30μm,片层间距0.90μm,前者的细化机理为相变重结晶细化了α相晶粒,后者细化片层组织的关键在于低温段(α2+γ)两相区热处理形成细小的双态组织。
The microstructure and microstructure of the TiAl alloy sheets were characterized by means of metallographic microscope, scanning and transmission electron microscopy. The formation mechanism and microstructure of the Ti-48Al at% alloy sheet were studied. The results show that the Ti-48Al alloy single-stage heat treatment can get the whole slice structure, the average grain size of about 150μm, the spacing between the layers of about 1.30μm. The formation process is that the γ phase nucleates in the (0001) plane of the α phase by dislocation dislocation and grows by incomplete dislocation slip and layer fault region expansion. Both cyclic heat treatment and bimodal heat treatment can refine the grain size of the sheet to 30μm and the sheet spacing of 0.90μm. The refinement mechanism of the former is phase transformation recrystallization and grain refinement of α phase grains, The key to the organization is the formation of small, two-phase microstructure by heat treatment in the low-temperature (α2 + γ) two-phase region.