Effect of yttrium and zirconium microalloying on the structure and properties of weld joints of a two-phase titanium alloy

Abstract

The effect of microalloying of the Ti-4.8Al-1.2Mo-2.6V-0.6Cr-0.25Fe titanium alloy with yttrium and zirconium on the phase composition, structure and mechanical properties of welded sheets was studied using light and transmission electron microscopy, X-ray diffraction analysis and microindentation-hardness testing. A differential thermal analysis was employed to model the welding thermal cycle. It was found that alloying with yttrium led to the precipitation of Y2O3 oxide particles resulting in refining the microstructure of the alloy. In addition, yttrium additions were shown to stabilise the b-phase of the alloy that decreases the hardness of the alloy. Keywords: microalloying, rare-earth elements, titanium alloy, welding U~inek mikrolegiranja zlitine titana Ti-4.8Al-1.2Mo-2.6V-0.6Cr-0.25Fe z itrijem in cirkonijem na sestavo faze, strukturne in mehanske lastnosti je bil raziskovan s svetlobno elektronsko mikroskopijo, z rentgensko difrakcijsko analizo in s testiranjem trdote mikroindentacije. Uporabili smo diferencialno termi~no analizo za pridobitev modela za varilni termi~ni cikel. Ugotovljeno je bilo, da legiranje z itrijem vodi k razpr{enosti Y2O3 oksidnih delcev, kar se ka`e pri rafiniranju mikrostrukture zlitine. Poleg tega je bilo dokazano, da so dodatki itrija stabilizirali b-fazo v zlitini, ki zmanj{uje trdoto zlitine.

The Effect of Zirconium and Yttrium Oxide on the Microstructure and Mechanical Properties of Ti-Si-Zr Based Composites

“…The microhardness of the M3 composite is lower than the M2 composite because Y 2 O 3 oxide stabilizes the β phase by binding the oxygen in the composite and reduced the hardness. [38] Fig. 5 XRD diagrams of sintered composites.…”