Microstructural evolution of TiC/near-[...]Ti composite during high-temperature tensile test

• Published in: Journal of materials research 2016-11, Vol.31 (21), p.3428-3436
• Main Authors: Qi, J Q, Lu, J, He, Y Z, Sui, Y W, Meng, Q K, Wei, F X, Wei, Z J
• Format: Article
• Language: English
• Subjects: Deformation; Ductility; Dynamics; Evolution; Experiments; Materials research; Microscopy; Microstructure; Powder metallurgy; Recovery; Softening; Strain; Stress-strain curves; Stress-strain relationships; Temperature; Tensile strength; Titanium alloys; Trends; Yield stress
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/jmr.2016.359

In the present paper, 10 vol%TiC/Ti-6Al-3Sn-3.5Zr-0.4Mo-0.75Nb-0.35Si composite produced via in situ casting technique was tested in the temperature range from room temperature to 900 °C and much attention was paid on the microstructural evolution during high-temperature tensile test. It was found that the variation of microstructures in deformation zones with strain exhibited different trends at different temperatures. Below 600 °C, dislocation density increased with strain over the entire strain range. As temperature increased to 700 °C, dislocations proliferated rapidly in the initial deformation and then dislocation annihilated through dynamic recovery. Above 800 °C, the variation of microstructures in deformation zones with strain was similar to that at 700 °C at the beginning but at higher strain, dynamic recrystallization (DRX) occurred, leading to the formation of equiaxed microstructure. Microstructural evolution in deformation zones corresponded to the variation of tensile stress-strain characteristics with temperature, reflecting the hardening or softening feature of matrix. Dynamic recovery ascribed to the flow softening of the composite at 700 °C, while flow softening is owing to dynamic recovery and DRX above 800 °C. In addition, matrix softening should show different trends in different temperature ranges.