ENERGETICS OF TERNARY AND QUATERNARY ALLOY SURFACES

In spite of the advance in theoretical modelling of surfaces, there ar e a Limited number of investigations on the characteristics of multico mponent alloy surfaces. Moreover, the corresponding experimental work does not compare in scope and depth with the work done on binary alloy surfaces. Recent developments in computational modelling using semiem pirical methods both in the fields of alloy design as well as surface analysis: hint to the possibility of exploiting the predictive power o f these methods towards a comprehensive analysis of multicomponent all oy surfaces. In this work, we apply the BFS (Bozzolo-Ferrante-Smith) m ethod for alloys to determine the essential features of multicomponent alloy surfaces. Several issues will be illustrated, ranging from the influence of ternary additions to the surface composition of (110) sur faces of binary alloys (Ti or Cr additions to NiAl), the composition a nd energetics of ternary (Ni-Al-Cr and Ni-Al-Ti alloys) alloy surfaces and quaternary (Ni-Al-Ti-Cr and Ni-Al-Ti-Cu) alloy surfaces.