Abstract
In this paper, the rolled TiB whisker (TiBw)/Ti65 composites with different rolling reductions were obtained by high temperature (HT) rolling in the β single-phase region. The changes in TiBw, silicide and grain size after rolling deformation were analyzed by microstructure characterization. Based on this, the strengthening mechanism and HT deformation behavior of rolled composites were analyzed in combination with room temperature and HT tensile experiments. The results show that TiBw fractured after rolling deformation, leading to a decrease in the aspect ratio and an increase in matrix connectivity. Silicide with an average diameter of 80 nm appeared in the rolled composites. The grain was continuously refined as the rolling reduction increased. A T-type texture with the crystal C-axis parallel to the transverse direction appeared at 40% rolling reduction. The strength and plasticity of sintered TiBw/Ti65 composites were increased after rolling. With an increase of rolling reduction, the composites exhibited fine-grain strengthening below 650 °C. When tensile above 700 °C, a softening effect occurred with the decrease of grain size, that is, the yield strength decreased for grain size <3.6 μm. The strengthening mechanisms of rolled TiBw/Ti65 composites include fine grain strengthening, load transfer strengthening of TiBw, Orowan strengthening of silicide, and dislocation density strengthening. Among them, fine grain strengthening and load transfer strengthening predominated and increased as the rolling reduction increased. After tensile at 750 °C, many recrystallized grains with large misorientation appeared around the initial coarse grains and TiBw.
Published Version
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