Preparation and microstructure of Fe₃Al/Al₂O₃ composites reinforced by surface modified carbon fiber

The short carbon fiber (CF_s)/Fe₃Al-Al₂O₃ composites were prepared by a sol-gel dispersing method and a subsequent hot-pressing process. The Cu coating and SiC coating applied to CF_s were fabricated by electrochemistry and in-situ reaction method, respectively. The effects of Cu coating and SiC coating applied to carbon fiber on the microstructure, phase composition, mechanical properties and fracture behavior of CF_s/Fe₃Al-Al₂O₃ composites were investigated. The results show that the CF_s/Fe₃Al-Al₂O₃ composites fabricated from the as-received CF_s exhibit low density and the flexural strength is only 239.0 MPa comparable with matrix due to the CF_s severely eroded in Fe₃Al-Al₂O₃ matrix. The Cu coating applied to CF_s can effectively protect CF_s eroded by matrix, improve sintering compactness and cause strong bonding between the fiber and matrix that cause high flexural strength, however, the length of fibers extending from the matrix is short during the fracture process. The CF_s/Fe₃Al-Al₂O₃ composites fabricated from SiC coating exhibite homogeneous microstructure, the coating onto fiber is integrated and soft bondings between fiber and matrix result in the fiber with SiC coating extending from matrix or SiC coating remained in the pull-out holes. The weak interaction between the fiber with SiC coating and matrix greatly promotes fiber debonding and extending from matrix to promote toughening and progressive failure mechanisms in the CF_s/Fe₃Al-Al₂O₃ composites.