In situ control of AlCuFe thin film crystallization using optical pyrometry

Al62Cu25.5Fe12.5 quasicrystalline films are formed by annealing of successive and simultaneous deposition of the three elements. In situ pyrometrical control during temperature increase of annealing treatment points to a break in the radiative transfer only during the heating of films obtained by successive deposition. This discrepancy between the two processes is interpreted as being linked to the differing crystallization paths of the two initial mixtures. The discontinuity which appears at 730 K is attributed to the appearance of β and ω-AlCuFe ternary phases in the mixture. In situ pyrometrical control is used to optimize the annealing treatment of this kind of thin deposit and to access a value of heat capacity equal to 710 J/kg K for T > 720 K. This pyrometrical measurement can thus be regarded as a simple way to perform non-destructive differential thermal analysis measurements on ultra thin deposits.