Effect of Hydrogenation Treatment on Grain Refinement of Reaction Sintered Ti-6Al-4V Alloy Composites

Abstract

The current study was conducted to develop a Ti-6Al-4V alloy composite material with a fine structure with improved mechanical properties by precipitating TiC particles via reaction-sintering and, additionally, by incorporating the effects of hydrides formed by hydrogenation treatment, using powder to which Mo 2 C had been added. The effects of precipitated TiC particles, and the subsequent generation of hydrides by hydrogenation treatment, heavy-strain working, and recrystallization treatment on grain refinement during the forming process were studied by means of structural observations. Warm rolling and multi-axial alternate forging (MAF) were employed as the heavy-strain working methods. The base metal structure of the Ti-6Al-4V composite material prepared by hydrogenation treatment on the sintered body prepared by spark plasma sintering (SPS) contains particles with a grain size not greater than 1 mm, which become finer with increasing hydrogen content. The particle size of TiC formed by reaction sintering, however, is not changed by heavy-strain working after hydrogenation. Its room temperature tensile strength increases with the amount of TiC precipitation, and is higher than that of non-hydrogenated material.

Strength and Formability of Fine-Grained Laminated Magnesium Alloy

“…Note that the value of K Ic for the LCM laminated with the Ti foil is about twice that of individual Mg and Al alloys. The value K Ic for Ti alloys is about 108 MPa･m 1/2 [7], but the volume fraction of Ti in the LCM is less than 1%. However, the fracture toughness of the LCM improved as a result of the presence of finely dispersed Ti produced at the Al alloy side of the bonding interface by the warm-rolling process.…”

Grain Refinement and Mechanical Properties of Magnesium Alloy by Hydrogenation Treatment

“…The sever strain processing methods such as MA (Mechanical Alloying), ECAP (Equal Channel Angular Pressing), ARB (Accumulative Roll-Bonding), MAF (Multi-axial Alternative Forging), and MDF (Multi Directional Forging) are useful for grain refinement for enhancing the strength materials. [1]- [5] In this study, we combined the hydrogen absorption methods [6], [7] to the MAF method for grain refinement.…”