Formation mechanisms of Ti&lt;sub&gt;2&lt;/sub&gt;AlC and Ti&lt;sub&gt;3&lt;/sub&gt;AlC during solid-state sintering between multilayer graphene and TiAl alloy composite

Ming-Yu Wu,Xu Huang,Pei-Jie Li,Guang-Bao Mi

doi:10.7498/aps.71.20220845

Abstract

Ti2AlC and Ti3AlC formed by the reaction between C and TiAl alloy can improve the plasticity and strength of TiAl alloy respectively. Generally, the peritectic reaction of L + TiC→Ti2AlC (Ti3AlC) occurs in the process of liquid-phase sintering, but different formation mechanisms of Ti2AlC and Ti3AlC may exist in the solid-state sintering. In this work, multilayer graphene is employed to fabricate the reaction interface with TiAl alloy under 1100–1350 ℃, which is the common solid-state sintering temperature of TiAl alloy. According to the microstructure characterization and analysis, Ti2AlC and Ti3AlC are verified to contain no TiC. The interface energy values of TiC/TiAl, Ti2AlC/TiAl and Ti3AlC/TiAl are calculated to be about 1.2, 0.87 and 0.39 J·m2, respectively, indicating that Ti2AlC and Ti3AlC can be formed directly without TiC mesophase. Besides, only Ti2AlC is observed to be formed at 1150–1250 ℃, while the interface products at 1250–1350 ℃ change into Ti3AlC with a small amount of Ti2AlC. The mechanism that the sintering temperature affects the formation tendency of Ti2AlC and Ti3AlC can be ascribed to the content of α phase. The TiAl alloy matrix is composed of γ and a few α phases at 1150–1250℃, but almost completely transforms into α phase at 1250–1350 ℃, and the increase in the α content can promote the formation of Ti3AlC. The above results demonstrate the possibility of regulating the relative content of Ti2AlC and Ti3AlC through controlling the sintering temperature, which provides a promising method to improve the plasticity and strength of TiAl alloy.

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