INVESTIGATION OF THE THERMAL-STABILITY OF NI C MULTILAYERS BY X-RAY-METHODS/

Microstructural properties of Ni/C multilayers prepared by PLD (pulsed laser deposition) have been investigated after heat treatment in vacu um at temperatures in the range of 50 degrees C to 500 degrees C. X-ra y diffractometry, Xray reflectometry, fluorescence EXAFS (extended X-r ay absorption fine structure) and HREM (high resolution transmission e lectron microscopy) have been applied to characterize samples in the i nitial state and after annealing. The multilayer reflectivity remained unchanged or increased at temperatures below 400 degrees C due to sha rpening of the interfaces caused by the formation of a-nickel and nick el carbide. The reflectivity decreased at temperatures above 400 degre es C because of the fragmentation of the nickel layers. It can be show n, that both chemical and mechanical driving forces are responsible fo r the observed modifications of the initial specimen state.