Effect of secondary phases on electrical conductivity and thermal conductivity of HPDC Al-Ni and Al-Fe alloys: A comparative study

Solute atoms and secondary phases are the principal determinants of the electrical and thermal conductivity of aluminum (Al) alloys. However, the influence of secondary phases has often been undervalued compared to that of solute atoms. Herein, Al-Ni and Al-Fe alloys with gradient alloying contents were fabricated via high-pressure die casting (HPDC) to comparatively scrutinize the influence of the microscopic secondary phases on the macroscopic electrical and thermal conductivity of Al alloys. The results demonstrated that the microscopic conductive properties, morphology, and volume fraction of the secondary phases were the predominant factors influencing the electrical and thermal conductivity of Al alloys. Correspondingly, Al-Ni alloys demonstrated improved electrical and thermal conductivity, primarily due to the favorable microscopic electrical and thermal conductivity of their secondary phases, the elimination of morphology-induced electron scattering from needle-like secondary phases, and their comparatively lower secondary phase volume fractions. This research deepens the understanding of the microscopic secondary phase on macroscopic electrical conductivity and thermal conductivity of Al alloys, thereby contributing to the development of advanced Al alloys with enhanced conductive properties.