Microstructural stability of in-situ TiB2/Al composite during solution treatment

Abstract

The microstructural stability including grain growth and texture of in-situ TiB2/Al composite during solution treatment (ST) at T4 state (natural aging) was investigated for the first time. The results show that the nano TiB2 particles have a strong influence on the stability of grain size (GS) and textures during ST. The composite has exhibited improved stability of GS attributing to the Zener pinning of TiB2 particles, resulting in no obvious increase in GS after the ST for 24h. A modified Zener equation has been proposed for the composite with non-uniform particle distribution, which can make a good prediction on the limiting GS. For textures of the 2024 alloy and TiB2/2024 composite, there is not much difference in the intensity of 〈111〉 fiber before the ST, while the 〈l00〉 fiber is stronger in the composite. The 〈111〉 and 〈l00〉 double fibers of the composite are stabilized by TiB2 particles during ST at T4 state. However, the 〈111〉 and 〈100〉 fibers of the alloy are gradually replaced by 〈113〉, 〈102〉 and 〈302〉 ones due to the recrystallization and grain growth. Accordingly, the composite exhibits much stronger fiber textures than the alloy after the heat treatment.