A novel near α-Ti alloy prepared by hot isostatic pressing: Microstructure evolution mechanism and high temperature tensile properties

• A novel near-α high temperature Ti alloy was designed and formed by HIP process.
• Precipitation of silicide and α2 phase was determined by TEM.
• A successive evolution mechanism of the microstructure of HIPed parts was proposed.
• Reinforcement mechanism of the novel Ti alloy at high temperature was established.

This work presents a comprehensive study of the densification behavior, phase and microstructure development, high temperature tensile performance of a novel near-α high-temperature titanium alloy fabricated by hot isostatic pressing (HIP) at representative temperatures. The results indicated that numerous rod-like S2 silicides ((TiZr0.3)6Si3) and α2 phase (Ti3Al) precipitated from α matrix. The microstructural characteristics of HIP-fabricated parts experienced a successive change on increasing the HIP temperature: lathlike structure + little equiaxed grains → equiaxed grains + little lathlike structure → fully equiaxed grains. In addition, the grain size of samples unceasingly growed up with the increase of HIP temperatures. Over the entire tensile tests temperature range, the equiaxed grains plus little lath-like structure (HIP-B) exhibited the highest tensile strength. As to the ductility, the elongation of specimens increased successively with the increase of HIP temperatures, which is mainly due to the type of microstructure and the diffusion-metallurgical bond.

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