The hot deformation behavior and microstructure evolution of an in-situ TiB 2 /2024Al composite and its unreinforced 2024Al matrix alloy were systematically investigated through isothermal hot compression tests. The results reveal that the flow stress of both materials is sensitive to temperature and strain rate. With increasing strain, the flow stress increases rapidly to a peak, then either stabilizes or decreases slightly before reaching a steady state. The peak stress decreases with increasing temperature and decreasing strain rate. Under identical deformation conditions, the TiB 2 /2024Al composite exhibits higher flow stress than the 2024Al alloy. Arrhenius constitutive equations with and without strain compensation were established for the TiB 2 /2024Al composite. Incorporating strain dependence enhances the accuracy of flow-stress predictions. Processing maps indicate that a large instability domain exists at low strains, which gradually shrinks and disappears as strain increases. At high strain rates and elevated temperatures, the instability domain expands as strain increases. TiB 2 particles refine the grain size in both as-cast and hot-compressed TiB 2 /2024Al composites, while also reducing the size of coarse grain-boundary second phases. The primary softening mechanisms during hot compression are dynamic recovery (DRV) and dynamic recrystallization (DRX). The TiB 2 /2024Al composite exhibits a higher dynamic recrystallization fraction and subgrain content compared to the 2024Al alloy.
Li et al. (Fri,) studied this question.