Effects of Heat Treatment and In Situ Al ₃ Zr Reinforcement on Microporosity and Deformation Behavior of AA6061 Foams

Heat treatment of aluminum foams enhances their strength and energy absorption, expanding their industrial applications. However, the development of microporosity during heat treatment and its impact on deformation behavior are not well understood. This study examines the impact of aging and annealing treatments on the deformation behavior of in situ Al ₃ Zr/AA6061 foams produced via the melt route with a TiH ₂ blowing agent, focusing on microporosity evolution and mechanical property changes. Foams with porosities ranging from 60% to 80% were characterized using 4D X‐ray microscopy and compression testing, with microporosity effects investigated through finite element simulations. Solution heat treatment increased microporosity by 18%. Aged Al ₃ Zr/AA6061 foams exhibited a 53% higher plateau stress than AA6061 foams and reached 82% ideal energy‐absorption efficiency, despite showing brittle behavior with plateau fluctuations. The effect of microporosity was examined using both unscaled and scaled models; unscaled models incorporate microporosity into the existing macrostructure, while scaled models retain the same total porosity by reducing the macropore sizes. Unscaled simulations showed microporosity decreased properties by 25% while improving efficiency to 64%. Scaled models showed microporosity improved properties by 21% and efficiency to 67.7%. Precipitation strengthening from aging dominates over microporosity effects, resulting in net property enhancement despite increased microporosity.