Laboratory X-ray Diffraction Complex for In Situ Investigations of Structural Phase Evolution of Materials under Gaseous Atmosphere

Abstract

In this work, a laboratory X-ray diffraction complex for in situ investigations of structural phase evolution of materials under gaseous atmosphere and elevated temperatures was developed. The approbation of the complex was carried out using a commercially pure titanium (CP-Ti) powder, zirconium (Zr-1Nb) alloy and electron beam melted Ti-6Al-4V alloy. It was established that hydrogenation of the CP-Ti powder occurred at a temperature of 500 °C and a hydrogen pressure of 0.5 atm, accompanied by the formation of metastable γ titanium hydride (γ-TiH) phase. The lifetime of the γ-TiH phase was 35–40 min. Decomposition of the γ-TiH occurred after reaching a temperature of 650 °C as a result of the thermally stimulated desorption of hydrogen. The α-Zr → δ-ZrH phase transformation was observed under hydrogenation of the zirconium Zr-1Nb alloy at a temperature of 350 °C and a hydrogen pressure of 0.5 atm. It was revealed that the increase in hydrogenation temperature to 450 °C accelerated this transformation by two times. Hydrogenation of the electron beam melted titanium Ti-6Al-4V alloy at a temperature of 650 °C and hydrogen pressure of 0.5 atm was accompanied by the α → α + β → β + α2 phase transformations.

Keywords

• in situ XRD
• hydrogenation
• titanium alloys
• zirconium alloy
• electron beam melting
• thermal expansion coefficient