Ductile fracture behavior in TiC particle/a-b titanium alloy matrix composite
Hwang Jung Hwan; Ikai Yoshihito; Tagawa Tetsuya; Miyata Takashi
Abstract:Tensile deformation and ductile fracture process are investigated for titanium alloy matrix composite reinforced with TiC particles in comparison with Ti-6Al-4V alloy. Material used in this work is TiC/Ti-6Al-4V-11Cr composite produced by vacuum arc remelting process. TiC/Ti-6Al-4V-11Cr composite has strong interface between matrix and TiC particles because of in situ reaction process. Tensile tests for smooth and 1mmR notched round bar specimens are performed to investigate ductile fracture process and influence of stress triaxiality on it. Degradation in ductility due to the stress triaxiality is more significant in TiC/Ti-8Al-0.5Mo-0.5V composite than in Ti-6Al-4V alloy. Most of micro voids in composite are nucleated from cracking of TiC particles. Unit cell model combined with FEM analysis has revealed that the cracking of TiC particles are caused by mismatching with the matrix due to plastic strain and high stress triaxiality. Difference in process of micro void coalescence between smooth and notched specimens has been demonstrated in fractographic observation of fracture surfaces. Key Words:ductile fracture behavior, TiC/Ti-6Al-4V-11Cr composite, stress triaxiality, cracking of particles, void nucleation, growth, coalescence, dimple size distribution, unit cell model