Effect of hot-rolling temperature and reduction ratio on tensile properties of B4C-cBN reinforced aluminum matrix composite

초록

This study explores the effects of hot-rolling parameters on the microstructural evolution and tensile properties of aluminium (Al) matrix composites reinforced with boron carbide (B4C) and cubic boron nitride (cBN), fabricated via stir casting. Rolling was conducted at three different temperatures (150 degrees C, 300 degrees C and 450 degrees C) and reduction ratios (40 %, 55 % and 70 %). X-ray diffraction and electron back-scattered diffraction analyses revealed that both dynamic recovery (DRV) and dynamic recrystallization (DRX) were pronounced with increasing rolling-temperature and-reduction levels, resulting in the decreases of dislocation density and the increase of recrystallized grain fractions. Although the microstructural softening and dislocation recovery leads to a trade-off between strength and ductility, this study observed simultaneous increases in the ultimate strength (131.9 MPa), and the uniform elongation (0.52 %) and fracture elongation (3.07 %) with increasing reduction ratio. This anomaly is attributed to reinforcement fragmentation and redistribution, which promoted the Taylor strengthening and load transfer effects. These results suggest that optimized hot-rolling parameters can effectively enhance the mechanical performance of B4C-cBN reinforced Al matrix composites for neutron-absorbing applications.

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