How to join heat sensitive materials?

Vinzenz Bissig ,  Jolanta Janczak-Rusch 

Empa, Materials Technology and Research (Empa), Überlandstrasse 129, Dübendorf 8600, Switzerland

Abstract

The nanoeffects like melting point depression are creating new opportunities for joining of advanced materials. Thanks to that phenomenon, heat-sensitive materials like bulk amorphous or nanostructured materials can be brazed without loosing their advantageous properties due to extensive processing temperatures.

The aim of this work is to investigate the principles of the melting point depression on the example of AgCu eutectic nanostructured filler metal.

The magnetron sputtering was used to build a nanomultilayer structure of AgCu layers (2.3nm-30nm) separated by AlN diffusion barrier layer (9nm). The melting point depression of up to 130°C was observed by high-temperature XRD measurements. The experimental results show, on the contrary to the theoretical predictions, no inverse relationship to the layer thickness of the brazing filler. However, the energetic character of the interface that depends on the AgCu layer thickness has to be considered. Thin AgCu layers (≤7nm) show semi-coherent interface resulting in a superlattice, measured by XRD. These interfaces are energetically more stable, than a random orientation interface observed for thicker AgCu layers. In future, designing the diffusion barrier layer would allow tailoring the properties of the interface and maximize the beneficial effect of the melting point depression.

 

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Presentation: Oral at E-MRS Fall Meeting 2009, Symposium H, by Vinzenz Bissig
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-27 17:16
Revised:   2009-08-24 15:57