Effect of ZrMgMo₃O₁₂ content on the thermal expansion and dimensional stability of ZrMgMo₃O_12p/2024Al composites

With an increasing temperature gradient, the internal stress in composites can cause many problems, such as the plastic yield of the matrix, fracture of the reinforcements, growth of pores in the matrix, and debonding of the interface. The reinforcement particularly affects the internal stress, considerably changing the various properties of the composites. ZrMgMo₃O_{12particle (p)}/2024Al composites were fabricated using 5−30 vol. % of a near-zero expansion material, ZrMgMo₃O₁₂, as a reinforcement. This was achieved via high-energy milling followed by vacuum hot pressing. The influence of the ZrMgMo₃O₁₂ content on the thermal expansion and dimensional stability of the composites was investigated. The results indicated that the large thermal mismatch stress between ZrMgMo₃O₁₂ and 2024Al limited the addition of ZrMgMo₃O₁₂ to the composites. The composites with 30 vol. % ZrMgMo₃O₁₂ failed after solid solution treatment during water quenching. With increasing ZrMgMo₃O₁₂ content from 5 to 20%, the coefficients of thermal expansion (CTEs) first decreased and then increased, whereas the dimensional stability of the composites first increased and then decreased. The composites with 10% ZrMgMo₃O₁₂ had the lowest CTE of 11.3 × 10^–6 °C⁻¹ from − 100 °C to 400 °C, and exhibited dimensional stability from room temperature (RT) to 400 °C.