Formation of Multiphase Soft Metal from Compositing GaInSn and BiInSn Alloy Systems

Emerging functional room-temperature liquid metals generally include gallium-based and bismuth-based alloys. Their excellent electrical conductivity, thermal conductivity, flexibility, fluidity, and reflectivity can enable their application in many fields. However, there are quite a few problems that need to be solved before their application. For example, liquid metals are often difficult to adhere and diffuse on solid substrates due to their high surface tension and fluidity, which hinders the application and promotion. Herein, we report a method to develop multiphase soft metals from gallium- and bismuth-based alloys. Particularly, room-temperature multiphase soft metals of GaBiInSn alloys developed from Ga67In20.5Sn12.5 and Bi33.1In51.3Sn15.6 alloys via compositing, mixing, and heating treatment are first reported, which include the solid phase, liquid phase, and paste phase, respectively. The free metal alloy grains are dispersed in GaBiInSn alloys and transition constantly among different phases. More importantly, the structure, size, density, and other characteristics of free metal alloy grains can be modified by adjusting the mass ratio of each component. The surface morphology, structure, wettability, adhesion, work function, and photoelectric characteristics of multiphase soft metals can be controlled and optimized by controlling phase transition. As a result, the wettability of the obtained Ga50.25Bi8.28In28.2Sn13.27 is obviously improved (the contact angle decreased from 118.5° to 94°), with a high work function (4.75 eV), high reflectivity (78.14%), low electrical resistivity (2.94 × 10–7 Ω m). Meanwhile, several typical applications of the multiphase materials were demonstrated. The results of this work will offer a promising strategy to directly prepare liquid metal flexible electrodes on PI, PET, and silk, and also, the stability can be kept well under large deformation and curling conditions.