Investigations of Phase Transformations in a Blended Elemental Ti-Nb-Zr-O Alloys Prepared by a Field-assisted Sintering Technique

Abstrakt

Several Ti-Nb-Zr-O alloys were prepared as gradient samples from elemental powders, followed by compaction by field-assisted sintering technique (FAST). The gradient was created in Nb content for each sintered sample.

The chemical and phase composition of the solution treated conditions was investigated using scanning electron microscopy and X-ray diffraction. Elastic moduli were determined by resonance ultrasound spectroscopy of individual layers and mechanical behavior was studied by microhardness and compression testing. α" martensite is formed when Nb concentration is below 20 wt%.

Between 23 and 29 wt% Nb, ω phase is formed during quench and pure β is retained above 29 wt% of Nb. Elastic modulus is strongly influenced by the phase composition, ranging from 65 GPa (β) to 100 GPa (β+ω).

When O content is 0.5 wt%, several layers undergo a martensitic transformation β->α" during deformation, usually marking the presence of special effects, such as transformation induced plasticity or superelasticity.