The paper presents the results and provides an analyse of the geometric structure of Fe-Al protective coatings, gas-treated under specified GDS conditions. The analysis of the surface topography was conducted on the basis of the results obtained from the SEM data. Topographic images were converted to three-dimensional maps, scaling the registered amplitude coordinates of specific gray levels to the relative range of 0÷1. This allowed us to assess the degree of surface development by determining the fractal dimension. At the same time, the generated three-dimensional spectra of the autocorrelation function enabled the researchers to determine the autocorrelation length (Sal) and the degree of anisotropy (Str) of the surfaces, in accordance with ISO 25178. Furthermore, the reconstructed three-dimensional images of the topography allowed us to evaluate the functional properties o the studied surfaces based on the Abbott-Firestone curve (A-F), also known as the bearing area curve. The ordinate describing the height of the profile was replaced by the percentage of surface amplitude in this method, so in effect the shares of the height of the three-dimensional topographic map profiles of various load-bearing properties were determined. In this way, both the relative height of peaks, core and recesses as well as their percentages were subsequently established.

Mg-1.6Gd binary alloy was subjected to uniaxial warm rolling at a unidirectional and cross-sectional with a reduction ratio of 95% in order to observe the relationship between its microstructural changes to the degradation behavior. The warm rolling was performed at a temperature range of its recrystallization temperature, which were 400°C and 560°C, and a feed rate of 10 mm/min. Degradation behaviors of Mg-1.6Gd binary alloy was evaluated by means of potentiodynamic polarization and hydrogen evolution test in modified Kokubo’s SBF solution at temperature of 37 ± 1ºC. The lowest corrosion rate of 0.126 mm/year derived from potentiodynamic polarization test was showed by unidirectional-rolled specimen at temperature of 560 °C. Hydrogen evolution test results showed the lowest hydrogen gas formed during 24 hours of immersion was found on unidirectional-rolled specimen at temperature of 560°C with a rate of 0.268 cc/cm2/hours. While cross rolled specimens showed a high corrosion and hydrogen evolution rate of 20 mm/year and 0.28 cc/cm2/hours.