Research for Thermal Stability of Ti-6. 5A1-3. 5Mo-0. 2Si

摘要

The analysis of the microstructures and mechanical properties at room temperature about Ti-6. 5A1-3. 5Mo-0. 2Si titanium alloy bar,hot exposed blanks and hot exposed specimen is in this paper. Thermal stability's changing regularity and influences of the alloy were studied. Tensile test result at room temperature showed that alloy's tensile and yield strength increased 25MPa respectively;and percentage of blank's elongtation droppedslightly,percentage of specimen's elongtation fell 1. 5% when they were exposed after keeping 1000 hours at 500°C; percentage reduction of alloy's area fell 4. 5%,and materiars thermal stability dropped a little. When material had been hot exposed,primary a phase and the secondary a phase slice that was formed among p phase change microstructure (β-PCM), didn't precipitate a_2 phase; primary a phase grew bigger and formed convex by the trifurcate grain boundary; the secondary a phase slice grew slightly, β phase lessened and the inner microstructures changed,these main reasons brought about thermal stability dropping; after hot exposing there was oxide surface, the thickness was about 0. 2* μm and diffusion layer's thickness was about 1. 0μm, the oxygen effective area was 1. 2μm, these factors' effect on thermal stability was less.