Structure-property relationship of cast Ti-Nb alloys

• Published in: Journal of oral rehabilitation 2002-04, Vol.29 (4), p.314-322
• Main Authors: Lee, C. M., Ju, C. P., Chern Lin, J. H.
• Format: Article
• Language: English
• Subjects: Corrosion; Crystallography; Dental Alloys - chemistry; Dentistry; Elasticity; Hardness; Materials Testing; mechanical property; modulus; niobium; Niobium - chemistry; Pliability; structure; Structure-Activity Relationship; titanium; Titanium - chemistry
• ISSN: 0305-182X; 1365-2842
• DOI: 10.1046/j.1365-2842.2002.00825.x

The present work is a study of the microstructure, mechanical properties and corrosion behaviour of a series of binary Ti–Nb alloys with Nb contents up to 35 wt%, with emphasis placed on the structure–property relationship of the alloys. The results indicate that crystal structure and morphology of the Ti–Nb alloys are sensitive to the Nb content. The cast c.p. Ti has a hexagonal α phase with a lath type morphology. The alloys containing 15 wt% or less Nb are dominated by a hexagonal α′ phase with an acicular, martensitic structure. When containing 17·5–25 wt% Nb, the alloys are primarily comprised of an orthorhombic α′′ phase. With 27·5 wt% Nb, metastable β phase starts to be retained. With Nb contents higher than 30 wt%, the equi‐axed β phase is almost entirely retained. Small amounts of ω phase are detected in alloys containing 27·5 and 30 wt% Nb. Among all present alloys, Ti–10Nb and Ti–27·5Nb exhibit the highest strengths, while the α′′‐dominated (17·5 and 20Nb) and β‐dominated (> 30Nb) alloys have the lowest moduli. All Ti–Nb alloys show excellent corrosion resistance in Hank's solution at 37 °C. From the present data, the microhardness, bending strength and modulus of the various phases in Ti–Nb alloys are compared and tentatively summarized as follows: Microhardness: ω > α′ > α′′ > β > α (c.p. Ti) Bending strength: ω > α′ > α′′ > β > α (c.p. Ti) Bending modulus: ω > α (c.p. Ti) > α′ > α′′ > β