Tensile properties and damage behaviors of C _sf/Mg composite at elevated temperature and containing a small fraction of liquid

The mechanical properties of magnesium matrix composites reinforced by pyrolytic carbon coated short carbon fiber at temperatures close to and above the solidus temperature were investigated by tensile tests for the first time. Microstructural observations and fractographic analysis were carried out in order to reveal the damage mechanisms of the composites with different fraction of liquid. Tensile strength of the composites decreased monotonously with temperature, an exponential equation relating the tensile strength to temperature and liquid fraction was derived. The elongation increases monotonously with temperatures from 400. °C to 428. °C (solidus temperature), and then decreases gradually with increasing fraction of liquid except a trough at 432. °C. The composites almost have no ductility and cannot sustain tensile stress when the fraction of liquid reaches 8%. The amount and distribution of liquid phase in the composites directly determines their mechanical properties and damage behavior.