Comparison of the effects of Mg and Zn on the interface mismatch and compression properties of 50 vol% TiB2/Al composites

Abstract

Low ductility limits the extensive application of high volume fraction (>30 vol%) ceramic particle-reinforced metal matrix composites, and the simultaneous improvement of strength and ductility is still a challenge owing to the smaller amount of matrix contained in such composites. In this paper, the effects of various contents of Mg or Zn (0, 6, 10 and 14 wt%) on the interface mismatch and compression properties of 50 vol% TiB2/Al composite fabricated in situ are comparatively studied. The results indicate that Mg has a better refinement effect than Zn on the TiB2 ceramic particles. Mg can reduce the crystallographic mismatch degree of the Al/TiB2 interface. 6 wt% Mg simultaneously increases the σ0.2, σUCS and εf of the composite into 780 MPa, 1162 MPa and 10.68%, compared with the composite without the addition of Mg, increasing 8.5%, 2.8% and 30.6%, respectively. However, the addition of Zn leads to serious distortion of the Al lattice and deteriorates the interface matching degree of Al/TiB2, so the addition of Zn generally improves the σ0.2 and σUCS while sacrifices the plasticity simultaneously. Furthermore, the contributions of various strengthening mechanisms of the matrix in the high volume fraction TiB2/Al composites are analyzed through a comparative study.