Correlations between aging heat treatment, ω phase precipitation and mechanical properties of a cast Ti–Nb alloy

Cremasco, Alessandra; Andrade, Protásio N.; Contieri, Rodrigo José; Lopes, Éder Sócrates Najar; Afonso, Conrado Ramos Moreira; Caram, Rubens

doi:10.1016/j.matdes.2010.11.012

Cited by 63 publications

(40 citation statements)

References 10 publications

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“…However, from the extended stability diagram for titanium alloys proposed by Abdel and co-authors [18] based on averages of the electronic parameters, bond order (B o ) and d-orbital energy level (M d ), Ti-35Nb-7Zr alloy is locates between b + x and a 00 phase boundaries. Thus, the endothermic peak may include a 00 decomposition, precipitation of the x-phase and nucleation of the a-phase, as reported by other authors [10,16,19]. The other endothermic peak, around 700 K, has been related directly to the allotropic b-transus temperature.…”

Section: Structural and Thermal Characterizationsupporting

confidence: 62%

Anelastic relaxation associated to phase transformations and interstitial atoms in the Ti–35Nb–7Zr alloy

Chaves

Florêncio

Silva

et al. 2014

Journal of Alloys and Compounds

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Section: Structural and Thermal Characterizationsupporting

confidence: 62%

Anelastic relaxation associated to phase transformations and interstitial atoms in the Ti–35Nb–7Zr alloy

Chaves

Florêncio

Silva

et al. 2014

Journal of Alloys and Compounds

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“…However, previous DSC studies of binary Ti-Nb alloys did not detect this peak [11][12][13]. In that case dissolution of the α phase, which formed in the binary Ti-Nb alloys during the solution treatment, resulted in an endothermic peak at similar temperatures, presumably obscuring any exothermic heating effects associated with precipitation of the ω phase.…”

Section: Resultsmentioning

confidence: 74%

“…Exothermic peaks, detected for both the solution treated and cast materials, may be associated with precipitation reactions during heating [11][12][13]. The first peak at temperatures of between 300 and 400°C is in the range characteristic for precipitation of the metastable ω phase in Ti-Nb based alloys, which typically forms at lower temperatures than the equilibrium α phase [5,11,[14][15][16][17][18].…”

Section: Resultsmentioning

confidence: 98%

“…This may be due to the natural competition between the metastable α and ω phases as they form via decomposition from the β phase [15]. Alternatively, similar to the binary Ti-Nb alloys in which decomposition of athermally formed α occurred at similar temperatures to precipitation of the ω phase [11][12][13], decomposition of the stress induced α phase may obscure any exothermic heating effects during the DSC analysis.…”

Section: Resultsmentioning

confidence: 99%

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Thermal analysis of precipitation reactions in a Ti–25Nb–3Mo–3Zr–2Sn alloy

et al. 2012

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A study was undertaken on a Ti-25Nb-3Mo-3Zr-2Sn alloy using differential scanning calorimetry (DSC) in order to improve understanding of the precipitation reactions occurring during aging heat treatments. The investigation showed that isothermal ω phase can be formed in the cast and solution treated alloy at low aging temperatures. An exothermic peak in the temperature range of 300 to 400°C was detected for precipitation of the ω phase, with approximate activation energy of 176 kJ/mol. The ω phase begins to dissolve at temperatures around 400°C and precipitation of the α phase is favoured at higher temperatures between 400°C and 600°C. An exothermic peak with activation energy of 197 kJ/mol was measured for precipitation of the α phase. Deformation resulting in the formation of the stress induced α phase altered the DSC heating profile for the solution treated alloy. The exothermic peak associated with precipitation of the ω phase was not detected during heating of the deformed material and increased endothermic heating associated with recovery and recrystallisation was observed.

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“…Esse comportamento de rapassivação tem sido observado por outros autores em ligas de titânio e segundo os mesmos essa capacidade que o material tem de se repassivar exibe um importante papel na resistência à corrosão da liga [22][23]. É importante ressaltar que de acordo com a Tabela 1, todas as ligas apresentam valores de densidades de corrente de corrosão A/cm 2 , esses valores são característicos de ligas de titânio com elevada resistência à corrosão [24][25]. Outro fato interessante é que todas as ligas sofrem repassivação acima de 2000 mV e embora a liga Ti-35Nb-7,5Ta tenha a menor densidade de corrente de passivação mostrada na Tabela 1, é importante ressaltar que a liga Ti-35Nb-5Ta apresenta uma pequena passivação desde o início da curva, contudo esse filme é rapidamente quebrado em torno do potencial de 177 mV e só é refeito em uma densidade de corrente de passivação maior que a liga Ti-35Nb-7Ta.…”

Section: Ensaios Eletroquímicosunclassified

RESISTÊNCIA À CORROSÃO DE LIGAS Ti-35Nb-xTa EM SOLUÇÃO DE NaCl 0,9%

Macedo¹,

Matos²,

Souza³

2018

ABM Proceedings

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ResumoNeste trabalho, o comportamento eletroquímico das ligas Ti-35Nb-xTa (x = 0; 2,5; 5,0; 7,5)Ta (% em peso), solubilizadas e resfriadas em água, foi investigado em meio de NaCl a 0,9% mol/L através de testes de polarização anódica e medidas de impedância, micrografias e DRX. Os ensaios eletroquímicos mostraram que as ligas contendo tântalo apresentam uma maior resistência à corrosão que a liga sem tântalo. Além disso, os ensaios eletroquímicos em conjunto com as micrografias e DRX indicam que a composição Ti-35Nb-5Ta é a que apresenta maior resistência à corrosão no meio estudado, pois além de ocorrer uma estabilização da fase , o refino do grão foi menos pronunciado e por esse motivo minimizou o surgimento de microcélulas eletroquímicas. Palavras-chave: Ligas de titânio; Resistência à corrosão; Biomateriais. CORROSION RESISTANCE OF Ti-35Nb-xTa ALLOYS IN 0.9% NaCl SOLUTION AbstractThis work is a study of the electrochemical behavior of the Ti-35Nb-xTa alloys (x = 0, 2.5, 5, 7.5) (wt. %), solution treated and quenched in water. Anodic polarization tests and impedance measurements were carried out in these compositions by using a solution of 0.9% NaCl; their microstructures and XRD patterns were also obtained. The results showed that the alloys containing tantalum have a higher corrosion resistance than that one without Ta. In addition, electrochemical tests, together with the micrographs and XRD, indicate that the Ti-35Nb-5Ta composition is the most resistant to corrosion in the medium analyzed. This fact is a consequence of the stabilization of the  phase, and of its grain size, where the refinement effect of Ta is not enough strong and minimizes the formation of electrochemical microcells.

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Correlations between aging heat treatment, ω phase precipitation and mechanical properties of a cast Ti–Nb alloy

Cited by 63 publications

References 10 publications

Anelastic relaxation associated to phase transformations and interstitial atoms in the Ti–35Nb–7Zr alloy

Anelastic relaxation associated to phase transformations and interstitial atoms in the Ti–35Nb–7Zr alloy

Thermal analysis of precipitation reactions in a Ti–25Nb–3Mo–3Zr–2Sn alloy

RESISTÊNCIA À CORROSÃO DE LIGAS Ti-35Nb-xTa EM SOLUÇÃO DE NaCl 0,9%

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