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Vacuum brazing of TiAl alloy and 316L stainless steel (SS) was conducted using Zr-42.9Cu-21.4Ni amorphous filler metal. The effect of brazing temperature and brazing time on the microstructure and shear properties of the dissimilar metal joints between TiAl alloy and 316L stainless steel was investigated. The results show that the interface of the brazed joint can be divided into six different reaction layers. The microstructure of the brazed joints from TiAl alloy to 316L stainless steel at 1040 ℃/10 min is γ(TiAl)+AlCuTi/α2(Ti3Al)+AlCuTi/AlCu+ZrCuNi+FeZr/Cu8Zr3+ZrCuNi+TiFe+Fe2Zr/FeZr+Fe2Zr+TiFe2+ZrCu/α-(Fe, Cr). With the increase of brazing temperature, the shear strength of brazed joints increase first and then decrease. The maximum shear strength of 162 MPa is obtained at 1040 ℃/25 min. Fracture analysis indicates that cracks initiate at the interface of FeZr+Fe2Zr+TiFe2+ZrCu, and then propagate along Cu8Zr3+ZrCuNi+TiFe+Fe2Zr and α-(Fe, Cr) with cleavage fracture pattern.

The interfacial microstructure evolution, growth kinetics of the intermetallic compound (IMC) and mechanical properties of Fe/Al dissimilar metal joints were investigated by vacuum diffusion bonding. The results show that there is no IMC formed on the interface of the joint bonded at temperature of 550 ℃. When the bonding temperature exceeds 575 ℃, the interfacial region is composed of Fe2Al5 and a small amount of FeAl3, and the thickness of IMC layer increases rapidly with the increase of bonding temperature.Under the bonding time of 120 min, the shear strength of the joint increases first and then decreases with the increase of the bonding temperature, and the shear strength of the joint reaches the maximum value of 37 MPa.According to thermodynamic theory, the Gibbs free energy change of Fe2Al5 is the lowest in the range from 550 ℃ to 625 ℃, and then followed by that of FeAl3, and the generated sequence of interfacial IMC can be: Fe2Al5→FeAl3. The interfacial IMC grow in a parabolic manner as a function of bonding temperature, and its growth activation energy is 282.6 kJ·mol-1.The growth rates of IMC at the interface are 1.13× 10-14, 3.59×10-14, 1.21×10-13 m2·s-1 at 575, 600, 625 ℃ respectively.

Drainage basins are fundamental units of Earth's surface, describing how flows accumulate across landscapes. They are direct expressions of how tectonics and climatic forces alter Earth's surface morphology. Here, we measure the width‐to‐length ratios (WLRs) of 386,931 drainage basins (average area ∼157 km2), covering all continents except Antarctica and Greenland. Global variations in WLRs are correlated with climatic aridity, whole‐basin slope, and local topographic roughness. Basins in arid landscapes tend to be narrower, potentially reflecting a higher prevalence of surface runoff and therefore a stronger slope‐parallel component of the transporting flow. Local topographic roughness is associated with wider basins, potentially reflecting greater dispersion of flow directions. Conversely, whole‐basin topographic gradients, potentially reflecting gradients in uplift, are associated with narrower basins. However, steeper basins are also often rougher, so revealing the effects of whole‐basin slope requires correcting for the confounding effects of roughness variations. Plain Language Summary: Drainage basins are essential features that help us understand how water accumulates and flows across Earth's landscapes. In this study, we examined the width‐to‐length ratios of 386,931 drainage basins from all continents except Antarctica and Greenland. We found that basins tend to be narrower in more arid climates. We also observed that, all else equal, basins with greater local roughness tend to be wider, and those with steeper whole‐basin slopes tend to be narrower. Our results thus indicate that on the global scale, basin shapes are strongly influenced by topographic roughness, whole‐basin slope and climatic aridity. Our findings hold across different basin scales, encompassing smaller basins with a mean area of approximately 157 km2 to larger basins with a mean area of around 1,000 km2. These results advance our understanding of global patterns of basin shapes and the tectonic and climatic drivers behind them. Key Points: Globally, basins with greater topographic roughness tend to be wider, and those with steeper whole‐basin slopes tend to be narrowerIn arid regions (aridity index <0.65), basins tend to widen as climate becomes more humidBasin shape is strongly correlated with topographic roughness, whole‐basin slope and climatic aridity on a global scale [ABSTRACT FROM AUTHOR]

In order to improve joint integrity and reduce the amount of intermetallic compounds (IMCs), 6061-T6 Al and AZ31B Mg alloys were successfully joined by stationary shoulder friction stir welding (SSFSW). The stationary shoulder effectively enhanced the joint surface integrity and reduced the thickness reduction of the Al/Mg joint. The elimination of pin adhesion was beneficial to increasing material transfer and then improving interfacial joining length of Al/Mg joint. Extremely thin IMCs layer could be achieved because of the heat sink induced by the stationary shoulder. The maximum tensile strength of the Al/ Mg joint reached 137 MPa at a welding speed of 60 mm/min, rotating velocity of 1000 rpm and offset to Mg sheet of 0.3 mm, which was 130% higher than that of conventional joint. SSFSW is feasible and has the potential to join dissimilar materials with the formation of IMCs, such as Al/Mg alloys, Al/copper alloys, Al/titanium alloys and so on.