Influence of the Fiber‐Matrix Interface on the Strength of Unidirectional Carbon Fiber Reinforced Magnesium Composites

The mechanical properties of carbon fiber reinforced magnesium alloys strongly depend on the nature of the fiber-matrix interface. The interface strength is very low for pure magnesium since magnesium and C-fibers are a non-reactive system. As a result, the off-axis properties of the composites are rather poor. Two different approaches to enhance the interface strength are investigated: a) by carbide formation and b) by a TiN-fiber coating. The intensity of carbide formation increases with increasing aluminum content of the Mg-alloy and fiber reactivity. The formation of carbides produces a significant improvement of the off-axis properties at the expense of the in-axis strength. A TiN-coating inhibits the carbide formation. Improving the adhesion between fiber and matrix by a TiN-fiber coating enables a significant increase of the off-axis properties without negative influence on the in-axis strength.