Naslov
Microhardness characterization of Al-W thin films

Autori
Stubičar, Mirko ; Tonejc, Antun ; Radić, Nikola

Izvornik
Vacuum (0042-207X) 61 (2001); 309-316

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Al-W thin films; isochronal annealing; magnetron cosputtering; Vickers microhardness; X-ray diffraction
(Al-W thin films; isochronal annealing; magnetron cosputtering; Vickers microhardness; X-ray diffraction.)

Sažetak
Thin films of Al-W alloys were prepared on sapphire substrate by the magnetron cosputtering . By X-ray diffraction it was revealed that within a composition range Al80W20 to Al67W33 the films were X-ray amorphous. The increase of tungsten content in the films (Al60W40 and Al50W50) resulted in the appearance in a mixture of two or three metastable crystalline phases. Apparently the mixture of crystalline phases coexisted with a small fraction of amorphous one. Vickers microhardness of the as-prepared films varied from ~11 GPa for completely amorphous up to ~20 GPa for the films consisting of a mixture of phases. The thermal stability of films was investigated after isochronal annealing the samples for 1 h in a temperature range from 293 K to 1273 K. It was revealed that there was slight increase in the microhardness during annealing up to a temperature chosen within interval ~(773 -848) K, and such annealing has a small influence on the XRD patterns. In contrast, the annealing above this temperature interval induced detectable changes in the microhardness and a significant changes in X-ray diffraction patterns. The results of analysis of XRD patterns demonstrated that amorphous thin films do not disintegrate directly into the ordered equilibrium (a-W, Al4W, and Al5W) coexisting phases, but the metastable (a-W(Al), b-W(Al), and Al(W) ) intermediary phases were observed to appear in the films before the former phases were observed. Thus, for the microhardess behaviour during isochronal annealing of Al-W thin films an explanation given for the metallic glasses investigated earlier can be offered, and this explanation is based also on the results of the XRD investigation we performed.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Kemija

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