Mechanism of graphene oxide promoting silicide precipitation in high-temperature titanium alloy

Abstract

Graphene oxide (GO) can strongly promote the precipitation of silicide and improve the strength of high-temperature titanium alloys. However, it is difficult to control the precipitation location and size of silicide due to the unclear influence mechanism. In this paper, the mechanism of GO promoting silicide precipitation in high-temperature titanium alloy was studied by EPMA, SEM, TEM and theoretical analysis. With the increase of GO in the range of 0–0.50 wt%, the amount and size of silicide both increased significantly. The nanoscale silicide precipitated only at α/β phase boundaries in the high-temperature titanium alloy without GO, and microscale silicide precipitated simultaneously at α/β phase boundaries and in α phase when the amount of GO reached 0.30 wt%. The reason of GO promoting silicide precipitation was that the increase of α phase content by pinning phase boundaries and introducing C and O elements by GO led to the increase of Si concentrations in both α and β phases during hot isostatic pressing. Finally, the quantitative relationship between the maximum precipitation temperature of silicide and addition amount of GO was established to provide a basis for the composition and process design of GO reinforced high-temperature titanium matrix composites.