Interfacial shear strength behaviour of Ti/SiC metal matrix composites at room and elevated temperature

Evolution of crack-bridging and crack-tip driving force during the growth of a fatigue crack in a Ti/SiC composite

“…In order to make direct measurements, we developed a modified version of the single fibre fullfragmentation test in which the fragmentation process is examined by synchrotron X-ray diffraction in situ prior to full-fragmentation (Preuss et al 2002). Using this method, it has been shown that the frictional sliding stress of the interface for Ti-6Al-4V/SCS-6 SiC is dependent on the thermal-stress-related radial clamping force and so decreases from around 150 MPa at room temperature (RT) to 50 MPa at 400 • C (Withers et al 2010). More recently, we have used synchrotron diffraction to measure the distribution of interfacial strength along bridging fibres in the wake and ahead of a fatigue crack in individual fibres (Sinclair et al 2005) or plies (Hung et al 2009).…”

Damage accumulation during high temperature fatigue of Ti/SiCf metal matrix composites under different stress amplitudes

“…7(b) the slope in the fibre strain profile changes either side of the horizontal solid lines; this represents a change in the direction of the interfacial stress (Equation ( 2)), where the kink at |z| ≈ 0.3 mm corresponds to the transition point. The fact that the load redistribution behaviour in the region between the dotted and solid lines is different between those regions adjacent to the crack plane could indicate a partial-sliding/sticking region [9], or this could be due to the effect of the prolonged exposure to high temperature on the local interfacial properties [30] during the in situ measurement, or could be due to the convolution of the different conditions experienced by different fibres through the thickness. For fibres positioned well ahead of the fatigue crack tip (e.g.…”

“…During manufacturing, the cooling process causes radial clamping stressed on the fibres exerted by the matrix, due to the mismatch in coefficients of thermal expansion. This radial clamping stress decreases with increasing temperature, thus reducing Coulombic friction and leading to a lower interfacial sliding stress at elevated temperatures [9]. In addition, the nature of the interface can change significantly on exposure to high temperatures.…”

Measuring the stress field around an evolving crack in tensile deformed Mg AZ31 using three-dimensional X-ray diffraction

“…The software introduced above can be run iteratively, one phase at the time to give the stress distribution in both matrix and individual reinforcing fibres as a coarsegrained analogy to e.g. work by the Manchester group [11,52].…”