Lightweight and near-zero thermal expansion ZrW2O8-SiCnw/Al hybrid composites

Abstract

• We reported a novel hybrid design strategy to achieve near-zero thermal expansion and high strength Al matrix composites. • NTE ZrW 2 O 8 and lowCTE SiC successfully control the high CTE of Al. • The addition of SiC (particle and nanowire) significantly reduces the thermal mismatch stress of ZrW 2 O 8 /Al composites. • Yield stress rises by increasing the SiCnw content, resulting in reduction of the unfavorable high pressure γ-ZrW 2 O 8 and microcracks. Negative thermal expansion particles can compensate metal matrix composites to achieve near-zero thermal expansion materials. However, there are huge thermal residual mismatch stresses in the particles due to the thermal expansion mismatch between matrix and reinforcement. The use of hybrid reinforcement is required to solve the stress concentration problem. In this study, the hybrid Al matrix composites reinforced with ZrW 2 O 8 and SiC reinforcements (SiCp, SiCnw) were fabricated by the pressure infiltration process. The effect of SiC content on microstructure, phase composition, thermal expansion and mechanical properties were examined by a combination of XRD, SEM, thermal dilatometer and bending tests. The results showed that the high-pressure phase (γ-ZrW2O8) content of hybrid metal matrix composites decreased with increasing SiC fraction. Among them, the composites containing 61.7 vol%ZrW 2 O 8 and 3.3vol%SiCnw achieved the best performance with a bending strength of 100–150 MPa and a near-zero thermal expansion (2.0–3.0 ×10 –6 K −1 ) in a wide range of − 50–120 °C, which was attributed to the synergetic hybrid effects of SiCnw and ZrW 2 O 8 . This work opens up a new frontier for the design and preparation of lightweight zero-thermal expansion materials.