Directional mass transport of nano-confined metals and alloys in nanomultilayers

Nanomultilayers (NMLs) present an important class of nanomaterials, which find various applications in the fields of e.g. electronic, optical, medical and sensing devices. In recent years, NMLs consisting of alternating nanolayers (thickness ≤ 10 nm) of a metal or alloy (e.g. Ag, Cu, Ag-Cu, Al-Si) and a chemically-inert barrier material (e.g. AlN, W, C) have also been envisaged as nano-structured brazing filler for joining miniaturized devices and heat-sensitive (nano)materials at temperatures well below the bulk melting point of the respective bulk eutectic alloy [1-4]. As indicated by recent experiments [1-3] and theoretical predictions [4], the nanoarchitecture of such NML brazing fillers can be tailored to invoke extensive mass transport of the nano-confined metal to the NML surface at temperatures as low as 250°C, as realized by both stress-driven solid-state diffusion in possible combination with fast outflow of a liquid phase. Such low-temperature mass transport phenomena might be exploited for novel nano-technologies.

This contribution will give an overview of our latest experimental findings and model predictions on the thermal stability of nano-confined metals and alloys in a NML configuration with special emphasis on the underlying mechanism(s) governing directional mass transport of nano-confined metals and alloys [1-4]. The effect of the processing atmosphere on mass transport in Ag/AlN NML will be highlighted [1].

[1] M. Chiodi, C. Cancellieri, F. Moszner, M. Andrzejczuk, J. Janczak-Rusch, L.P.H. Jeurgens, J. Mater. Chem. C 4 (2016) 4927-4938.
[2] J. Janczak-Rusch, M. Chiodi, C. Cancellieri, F. Moszner, R. Hauert, G. Pigozzi, L.P.H. Jeurgens, Phys. Chem. Chem. Phys. 17 (2015) 28228-28238.
[3] J. Lipecka, J. Janczak-Rusch, M. Lewandowska, M. Andrzejczuk, G. Richter, L.P.H. Jeurgens, Scripta Mater. 130 (2017) 210-213.
[4] G. Kaptay, J. Janczak-Rusch, L.P.H. Jeurgens, J. Mater. Eng. Perform. 25 (2016) 3275-3284.