Revealing the ultra-high high-temperature compressive mechanical properties and deformation mechanism of a heterostructured AlNp/Al nanocomposite

Heterostructured materials have attracted increasing attention owing to their superior mechanical properties. In this work, the high-temperature mechanical property and deformation mechanism of a heterostructured AlNp/Al composite were revealed by isothermal compression tests. The results showed that the superior compressive strength of the AlNp/Al composite could be maintained at both room temperature and high temperature of 300-500 degrees C during the whole deformation process. The strong pinning effect of the dispersive AlN nanoparticle (AlNp) on the matrix grains could prevent grain boundary softening and grain growth, as well as the special layered heterogeneous structure and network structure could avoid high temperature softening. The hot deformation mechanism of the AlNp/Al composite could be affected by the strain rate and deformation temperature. It was confirmed that continuous dynamic recrystallization (CDRX) dominated the whole deformation process when deformed at low strain rates (0.0001-0.01 s-1) and high temperatures (400-500 degrees C); while dynamic recovery (DRV) was the main mechanism at high strain rate (0.1-1 s-1) and low temperature (300-350 degrees C) Furthermore, the strain rate sensitivity exponent (m) was used to assess the relationship between peak stress and deformation temperature and strain rate, which could predict the instability region of the composite. It shows that the simultaneous action of high temperatures and high strain rates should be avoided during hot deformation. This work shed light on the microstructure design of the high-strength heat-resistant aluminum matrix composite.