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[论文]Comment on Electrum,the Gold−Silver Alloy

Comment on “Electrum, the Gold−Silver Alloy, from the Bulk Scale to the Nanoscale:Synthesis, Properties, and Segregation Rules”

Wang YG, Tang SC,Vongehr S,Ali Syed J ,Wang XY and Meng XK

National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, College of Engineering and Applied Sciences, Institute of Materials Engineering, Nanjing University, Nanjing, Jiangsu 210093, P. R. China.

In a recent paper, Guisbiers et al. 1 published a nano-thermodynamic study on the phase diagram of bimetallic Au−Ag nanoalloy through considering the effects of lattice structure, shape, and surface properties of the particle on its material properties. They also proposed two segregation rules according to the relationship among immiscibility, melting temperature, and solid surface energy for bimetallic alloys. 1 However, their results and discussions are quite questionable.Their proposed first segregation rule says that the element with the highest melting temperature goes to the surface. The second segregation rule says that the element with the lowest surface energy will segregate to the surface, when the melting temperatures of both elements have more or less the same magnitude. In the case of total or partial miscibility, both the first and second rules apply, and in the case of total immiscibility, only the second segregation rule applies. 1 As shown in Table 2 of ref 1, Pt is miscible with Ni, and thus both the first and second rules apply to Pt−Ni alloy. However, both the melting temperature (2041 K) and surface energy (2.30 J/m 2 ) of Pt are larger than those of Ni (1728 K and 2.01 J/m 2 ). 2,3 Namely, the segregation of Pt obeys the first rule while is in violation of the second rule.

Scientific Reports,2016,6,12883.