Effect of Gd content on interfacial microstructures and mechanical properties of Cf/Mg composite

• The Gd element is prone to segregate to the interface between the fiber and matrix.
• Interfacial products including Gd2O3 and Mg7Gd are observed at interface.
• ILSS of Cf/Mg–3.2Gd composite is increased by 60.4% compare to that of Cf/Mg composite.

Matrix alloying is an effective and convenient method to improve the interface bonding strength for continuous carbon fiber reinforced magnesium matrix composites. In this work, rare earth metal Gd was selected as an alloying element to improve the interface bonding of Cf/Mg composite. Cf/Mg composites with different Gd content were fabricated by pressure infiltration method. The effect of Gd addition on the interfacial microstructures and mechanical properties of the composites were investigated. The results showed that the rare earth Gd tended to segregate at interface area to form Gd2O3 layer and particle phase Mg7Gd. Both the interfacial products enhanced the interface bonding strength which can be identified by the increase of interlaminar shear strength (ILSS). In particular, the Gd addition promoted the ILSS and bending strength greatly, with an increase by 60.4% and 25.3% compared with Cf/Mg composite, respectively. The fracture surfaces of the composites were examined by scanning electron microscopy and micrographs were employed to explain the inherent relation between interface characterization and mechanical properties.