Mechanical Response and Microstructural Evolution Mechanisms of 2 vol.% TiB/Ti-55531 Composites During Isothermal...

Area of Science:

• Materials Science
• Metallurgical Engineering

Background:

• Thermomechanical processing (TMP) is crucial for developing high-strength titanium alloys and composites.
• Understanding microstructural evolution during hot processing is key to optimizing material properties.

Purpose of the Study:

• To investigate the mechanical response and microstructural evolution mechanisms of 2 vol.% TiB/Ti-55531 composites during isothermal compression.
• To establish strain-compensated constitutive equations and elucidate dynamic recrystallization (DRX) and spheroidization mechanisms.

Main Methods:

• Isothermal compression experiments at varied temperatures (785-925 °C) and strain rates (0.001-1 s⁻¹).
• Kinetic calculations and detailed microstructural characterization.
• Construction of a microstructural evolution mechanism map.

Main Results:

• Deformation conditions influence flow behavior via dynamic recovery (DRV) and DRX of the beta phase, and dynamic spheroidization of the alpha phase.
• Three DRX mechanisms of the beta phase were identified, with TiB-induced DRX being dominant.
• Dynamic spheroidization mechanisms of the alpha phase, including beta-wedge penetration and alpha interaction/kinking, were elucidated.

Conclusions:

• TiB addition significantly promotes beta-phase DRX, randomizes crystallographic orientations, and enhances microstructural stability.
• An optimized hot-processing window was proposed based on the comprehensive microstructural evolution map.
• The study provides theoretical insights and practical guidance for hot processing and microstructure control of metastable beta titanium matrix composites.