Microstructure and mechanical response of TiB2/Al–Zn–Mg–Cu composites with more addition of Zn

Abstract In the present work, the in-situ TiB2/Al–Zn–Mg–Cu composites with different content of Zn element were fabricated by powder metallurgy. The interphases composed of solute elements are preferentially nucleated at the facets of the TiB2 particles during heating and the clusters in local region hinder the dissolution of the interphases into the matrix. Additionally, the phenomena of accelerated age-hardness response and reduced work hardening rate with increasing Zn content are found experimentally for TiB2/Al–Zn–Mg–Cu composites fabricated by powder metallurgy. A physically-based numerical model is developed to predict the precipitation kinetics and hardness as a function of aging time. The advanced reach to peak hardness results from accelerated nucleate rate and growth rate due to more addition of solute content. The influence of Zn content on the work hardening rate is discussed based on the state-parameters including solute content in the matrix, precipitate size and volume fraction. The effect of TiB2 particles on the parameters of the size class model is discussed qualitatively based on the experimental observations.