T. C. Tsai's research while affiliated with National Taiwan University and other places

Publications (7)

Article
The bond strength of the 6061-T6 aluminum alloy brazed with Al-12Si, Al-9.6Si-20Cu, and Al-7Si-20Cu-2Sn filer metals at a low temperature of 550°C is evaluated. The fractography of these brazements after tensile tests was observed using scanning electron microscopy (SEM). It was found that joints with good integrity can be produced with Al-7Si-20Cu...
Article
The study is concerned with developing low-melting-point filler metals for brazing aluminum alloys. For this purpose, thermal analyses of a series of Al-Si-Cu-Sn filler metals have been conducted and corresponding microstructures observed. The results showed that the liquidus temperature of Al-Si-Cu filler metals dropped from 593 °C to 534 °C, when...
Article
The manifestations of serrated yielding behavior at room temperature accompanied with the microstructural transitions in the 8090 alloy were systematically studied. Differential scanning calorimetric analyses in combination with transmission electron microscopic observations were employed to identify the microstructures for specimens tempered under...
Article
The effects of biaxial superplastic deformation and postforming heat treatment upon the stress corrosion cracking (SCC) of a fine-grained 7475Al alloy plate have been investigated. For all postforming tempered conditions, increasing the extent of superplastic deformation, which created more cavitations, would decrease the mechanical properties, the...
Article
The effect of grain size upon the stress corrosion cracking of 7475 Al-alloy plates has been investigated. Grain refinement resulted in a more homogeneous slip mode and a smaller size of grain boundary precipitates (GBPs) to influence the stress corrosion cracking (SCC) resistance. The more homogeneous slip mode is always beneficial for improving t...
Article
The influence of different heat treatments upon the atmospheric stress corrosion cracking (SCC) of fine-grained 7475 Al-alloy plates has been investigated. The small size of the matrix precipitates and grain-boundary precipitates (GBPs) was found to be the main cause of atmospheric SCC suscepti-bility. Increasing the size of the matrix precipitates...
Article
A relationship between electrical conductivity and stress corrosion cracking (SCC) resistance of the 7,000-series Al-Zn-Mg alloys has been established, although only from the near-peak strength T6 temper to the overaged T73 tempered condition. The present work investigated whether this relationship exists for all periods of aging and for Al alloys...

Citations

... It is known that the alloy electrical conductivity can be affected by electron scattering induced by GP zones and/or precipitates [42] and used to evaluate the effects of precipitate variation on SCC resistance of high-strength Al alloys, i.e., the higher the electrical conductivity, the better the SCC resistance [43][44][45][46] , in comparison with low-strain rate tension and static tensile methods. An effective RRA process and precise composition/processing control are required for achieving better integrated properties and ensuring the consistency of different batches for high-strength Al-Zn-Mg-Cu series alloy plates. ...
... It can be observed directly from Fig. 7 that the samples with the pre-stretching of 4% and 6% have larger GBPs, which can delay the brittle fracture of grain boundary to avoid the intergranular SCC. Moreover, due to the variation of the size of precipitates, the main dislocation strengthening mechanism in the alloy changes from cutting to bypassing, which reduces the planar slip of dislocations and leads to a single slip mode [31]. Thus, the aggregation of H atoms through the dislocation to the grain boundary reduces significantly. ...
... Due to its excellent properties such as good specific strength, low density, good surface finish, superior corrosion resistance, and good workability, aluminum and its alloys have been widely used in field of communications and transport [1,2], architecture [3] and package industries [4][5][6]. In the past decades, due to the huge lack of copper resources, the use of aluminum alloy is considerably increasing [7][8][9]. ...
... The effects of heat treatments and ambient temperature on mechanical properties and fatigue failure of aluminum alloys have also been studied. Tsai et al. [10] observed the microstructure of tensile test specimens and concluded that an over-aging treatment is effective to 4/20 prevent stress corrosion cracking at room temperature. Esmaeili et al. [11] examined the deformation behavior of AA6111 as a function of temperature and precipitates using work hardening behavior analysis and strain rate sensitivity measurements. ...
... (4) When laser-powder bed fusing dissimilar materials for example metals and ceramics where wetting may be an issue or when the melting temperature needs to be lowered in order to preserve the processing material properties, then a colloid intermediary bonding layer containing for example aluminium, copper, silver, nickel or tin compounds could be nebulised onto the powder beds [71][72][73][74]. (5) Silver, copper and aluminium are the most challenging materials for laser-powder bed fusion due to their low optical absorption in the near infrared [75,76]. ...
... Particles in 7xxx series aluminium have been associated with pits formed via multiple mechanisms (Tsai and Chuang 1996;Birbilis and Buchheit 2005;Holroyd and Scamans 2013), however, in moist air, coarse intermetallic phases are not seen to dissolve or cause localised corrosion. From Figs. 14, 15, 16 and 17, the fracture surfaces did not display any thick films or signs of corrosion. ...