Hot compression deformation characteristics of TiBw/Ti65 composites for high-temperature application

Ti-5.9Al-4.0Sn-3.5Zr-0.5Mo-0.3Nb-1.0Ta-0.4Si-0.8W-0.05C (Ti65) alloy is a high-temperature titanium alloy designed for service at 650 degrees C. To further improve the elevated temperature mechanical performance of Ti65, Ti65-based composites have been fabricated in the present study through a low-energy ball milling and reaction hot-press sintering process. Hot compression tests were further performed on the as-sintered TiB/Ti65 composites at the temperature ranging from 1040 to 1100 degrees C at the strain rate of 1-0.001 s(-1). The results show that during deformation at 1-0.1 s(-1), dynamic recrystallization was the dominant mechanism. At the low strain rate of 0.01-0.001 s(-1), dynamic recovery became the predominant mechanism. Hyperbolic constitutive equations were calculated and the processing maps were constructed based on dynamic material modeling. The activation energy for hot deformation was determined to be 321.57 kJ/mol and the ideal processing parameters for the network composite were 1070-1100 degrees C with a strain rate of 1-0.1 s(-1). The microstructural analysis of the hot compression-deformed samples revealed the presence of two dynamic recrystallization mechanisms: continuous dynamic recrystallization and discontinuous dynamic recrystallization. After hot compression, metallic matrix exhibited preferred orientation, including a strong <1210>//CD fiber texture and <0111>//CD fiber texture. Matrix flow induced TiB whiskers rotation, producing a pronounced [100]//CD texture and a weak [010]//RD and [010]//ND texture.