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Assessing the influence of heat treatments on γ-TiAl joints
Guedes, A.; Pinto, A. M. P.; Vieira, M. F.; Viana, FilomenaThe heat treatment of γ-TiAl alloy (Ti-47Al-2Cr-2Nb (at.%)) diffusion brazed joints was investigated. Joining was performed using a Ti/Ni/Ti clad-laminated braze alloy foil at 1050 and 1150ºC with a dwell time of 10 minutes. The joints were subsequently heat treated at 1250 and 1350ºC for 240 and 30 minutes, respectively. The microstructure and the chemical composition of the interfaces were analysed by scannin...
Joint Ti-47 Al-2Cr-2Nb with a Ti-Ni braze alloy
Guedes, A.; Pinto, A. M. P.; Vieira, M. F.; Viana, FilomenaTi-47Al-2Cr-2Nb was joined by diffusion brazing using a Ti-Ni clad-laminated filler alloy. Brazing was performed in the temperature range of 1000 to 1200ºC for 10 min. The microstructure and the chemical composition of the interfaces were studied by scanning electron microscopy (SEM) and by energy dispersive X-ray scans (EDS), respectively. The reaction between the gamma-TiAl alloy and the liquid produced inter...
Joining Ti-47Al-2Cr-2Nb with a Ti/(Cu,Ni)/Ti clad-laminated braze alloy
Guedes, A.; Pinto, A. M. P.; Vieira, M. F.; Viana, FilomenaThe joining of Ti-47Al-2Cr-2Nb using Ti-15Cu-15Ni (wt.%) as braze alloy was investigated. Experiments were conducted at 980 and 1000ºC for 10 min. The microstructure and the chemical composition of the interfaces were studied by scanning electron microscopy (SEM) and by energy dispersive X-ray spectroscopy (EDS), respectively. For both processing conditions the reaction between the gamma-TiAl alloy and the braz...
The Influence of the processing temperature on the microstructure of gamma-TiA...
Guedes, A.; Pinto, A. M. P.; Vieira, M. F.; Viana, FilomenaThe joining of Ti-47Al-2Cr-2Nb (at.%) by diffusion brazing at 1000, 1050 and 1100ºC for 10 min, using a Ti-15Cu-15Ni (wt.%) braze alloy was investigated. The icrostructure and the chemical composition of the interfaces were studied by scanning electron microscopy (SEM) and by energy dispersive X-ray scans (EDS), respectively. The reaction between the gamma-TiAl alloy and the braze alloy led to the formation of ...
Microstructural characterisation of gamma-TiAl joints
Guedes, A.; Pinto, A. M. P.; Vieira, M. F.; Viana, Filomena; Vieira, M. T.; Ramos, A. S.The joining of a gamma-TiAl alloy using Incusil-ABA as filler metal was investigated. Bonding was performed in a high vacuum furnace at 750 ºC for 10 min. The interfacial microstructure was analysed by SEM and its composition was investigated by EDS. An intense diffusion of Ti and Al to the interface and a strong reaction between the braze alloy and the base metal were observed. The interface could be divided i...
Multilayered interface in Ti/macor machinable glass-ceramic joints
Guedes, A.; Pinto, A. M. P.; Vieira, M. F.; Viana, FilomenaMacor® machinable glass-ceramic and commercially pure (cp.) titanium were joined by active metal brazing, using a 64Ag–34.5Cu–1.5Ti (wt.%) filler alloy. The influence of the brazing temperature and holding stage on the microstructure and hardness profile of the interface, as well as on the shear strength of the joint, were assessed. Brazing was performed in a high vacuum furnace at 850, 890 and 930°C for 10 an...
Zr bearing gama-TiAl induction melted
Barbosa, J.; Duarte, António; Ribeiro, Carlos Silva; Viana, Filomena; Monteiro, A. CaetanoThis paper describes the processing results of TiAl alloys melted under argon atmosphere by induction melting, using crucibles made of calcia and stabilized zirconia. Castings were allowed to solidify inside the crucible, in order to simulate the worst situation using this processing. Segregation profiles of residual elements and microhardness of different phases were evaluated, as well as its relation with the...
The effect of brazing temperature on the titanium/glass-ceramic bonding
Guedes, A.; Pinto, A. M. P.; Vieira, M. F.; Viana, FilomenaThe aim of this work is to study the effect of time and brazing temperature on the interfacial microstructure and mechanical properties of the joint obtained by active metal brazing between c.p. titanium and a fluorosilicate machinable ceramic±glass using a 64Ag-34.5Cu-1.5Ti (wt%) brazing alloy. The reaction between the brazing alloy and the two materials leads to the formation of several interfacial reaction l...
Retrogression and re-ageing of 7075 aluminium alloy : microstructural character...
Viana, Filomena; Pinto, A. M. P.; Santos, Henrique; Lopes, A. B.Industrial Summary: The 7075 aluminium alloy presents a low stress corrosion cracking strength when aged to achieve maximum mechanical strength, T6 temper; high stress corrosion cracking strength is attained with overageing, T7 temper; but with loss of mechanical strength. Retrogression and re-ageing treatments improves the stress corrosion behaviour of the alloy whilst maintaining the mechanical resistance of ...
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