Influence of heating rate and aging temperature on omega and alpha phase precipitation in Ti35Nb alloy

Journal Article · Thu Nov 15 04:00:00 EST 2018 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2018.08.035· OSTI ID:22805843

Mello, Mariana G. de, ^[1]; Dainese, Beatriz P. ^[2]; Caram, Rubens ^[1]; Cremasco, Alessandra ^[2]

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1. University of Campinas (UNICAMP), School of Mechanical Engineering, Campinas, SP 13083-860 (Brazil)
2. University of Campinas (UNICAMP), School of Applied Sciences, Limeira, SP 13484350 (Brazil)

Highlights: • The heating rate, isothermal temperature and aging time strongly affect the phase precipitation. • Aged Ti35Nb alloy presented an ultimate tensile strength of 972 MPa with elongation of 7.5%. • The elastic modulus of 78 GPa makes this aged alloy a promising candidate for biomedical application. - Abstract: Metastable β Ti alloys based on Nb exhibit features that make them suitable for load-bearing biomedical applications, so it is crucial to evaluate their phase transformation and properties. This paper discusses the effects of aging heat treatments on the microstructure, phase transformation and mechanical behavior of Ti35Nb alloy. Samples were solution heat treated in the β field, quenched and aged under different conditions of heating rates, isothermal aging temperature and isothermal aging time. To enhance the alloy's mechanical behavior, thermal analysis and high temperature X-ray diffraction experiments coupled with Vickers hardness tests were employed to determine the temperature range of isothermal ω phase precipitation, as well as α phase precipitation temperature, thereby providing information to optimize aging heat treatment conditions. Results indicate that Ti35Nb alloy subjected to a heating rate of 30 °C/min and an isothermal aging temperature of 500 °C applied for 4 h would ensure high mechanical strength and low elastic modulus. The application of these aging conditions led to a microstructure consisting of very refined α phase precipitates homogeneously dispersed in the β phase matrix, presenting an ultimate tensile strength of 972 MPa, elongation of 7.5% and elastic modulus of 78 GPa, making this aged alloy a promising candidate for biomedical applications. These results shed light on the correlations between phase transformations, microstructure and mechanical behavior in high solute content TiNb alloys for biomedical applications.

• OSTI ID: 22805843
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 145; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AGING
BINARY ALLOY SYSTEMS
HEAT TREATMENTS
MICROSTRUCTURE
NIOBIUM COMPOUNDS
PHASE TRANSFORMATIONS
PRECIPITATION
PRESSURE RANGE GIGA PA
PRESSURE RANGE MEGA PA 100-1000
TENSILE PROPERTIES
THERMAL ANALYSIS
TITANIUM COMPOUNDS
X-RAY DIFFRACTION