Aging Behavior of In-Situ TiB₂ Particles Reinforced 2014Al Alloy Composites

Abstract

In-situ TiB₂ particles reinforced 2014Al alloy matrix composite was prepared using an exothermic reaction process with K₂TiF₆ and KBF₄ salts. The age-hardening behaviors of in-situ TiB₂/2014Al composites were studied using Vickers-hardness measurement, DSC and TEM. The results indicated that TiB₂ particles had a considerable effect on the aging response of 2014Al alloy matrix in the composite. Due to the introduction of TiB₂ particles, the time to achieve peak hardness in the composite is shorter at three aging temperatures compared with that of 2014Al alloy. While the age-hardness efficiency of the composites was lower than that of 2014Al alloy. Formation of G.P. zones was suppressed in composite, which was believed to be due to the introduction of vast particle-matrix interfaces that acted as a sink for vacancies during quenching. Moreover, TiB₂ particles caused increase in thermal-diffusion activation energy of θ′ phase during aging, which made the precipitation of θ′ phase more difficult. And the number and size of precipitates in the composite were relatively less and smaller than that of 2014Al alloy.