Microstructure and strength of Al-sapphire interface by means of the surface activated bonding method

Sapphire (alpha-Al2O3) and Al were joined by means of the surface activated bonding (SAB) method in an ultrahigh vacuum at room temperature. Tensile tests have shown that failure occurred not along the interface but inside the Al bulk near the interface. High resolution transmission electron microscopy has revealed the formation of a direct interface between Al and sapphire, indicating the possibility to artificially fabricate an atomically direct interface of dissimilar materials at room temperature. However, an intermediate layer was partially observed, which might be attributed to the effect of fast atom beam irradiation of the sapphire surface.