Al/Hf ratio-dependent mechanisms of microstructure and mechanical property of nearly fully dense Al–Hf reactive material

Abstract

This study proposed three types of Al–Hf reactive materials with particle size ratios (α), which were almost completely dense (porosity of <5.40%) owing to their preparation using hot-pressing technology. Microstructure characteristics and phase composition were analyzed, and the influence of particle size ratios on dynamic mechanical behavior and damage mechanism were investigated. The prepared sample with α = 0.1 exhibited continuous wrapping of the Hf phase by the Al phase. Hf–Hf contact (continuous Hf phase) within the sample gradually increased with increasing α, and a small amount of fine Hf appeared for the sample with α = 1. The reactive materials exhibited clear strain-rate sensitivity, with flow stress σ0.05 and failure strain εf increasing approximately linearly with increasing strain rate ε˙. It is found that the plastic deformation of the material increased with increasing strain rate. As α increased from 0.1 to 1, the flow stress gradually increased. Impact failure of the material was dominated by ductile fracture with a large Al phase plastic deformation band for lower α, while brittle fracture with crushed Hf particles occurred at higher α. Finally, a constitutive model based on BP neural network was proposed to describe the stress-strain relationships of the materials, with an average relative error of 2.22%.

Keywords

• Reactive material
• Particle size
• Split Hopkinson pressure bar test
• Stress–strain relationship
• Impact failure
• BP neural network