Influence of valence electron concentration over the friction behaviors ofquasicrystal and B2-type approximants in Al-Cu-Fe ternary system

Quasicrystals and their approximants are Hume-Rothery compounds having simi lar valence electron concentration. According to the valence electron conce ntration criterion for approximants, some B2 superstructures can be regarde d as a special group of approximants. The present paper reports on an inves tigation of dry friction behavior of this group of phases. The results are compared with the data from quasicrystalline and related crystalline phases with similar composition. Specifically, we show that samples containing th e B2 structure and its superstructures exhibit friction coefficients that d ecrease with increasing e/a and reach a minimum at 1.86, the value of the q uasicrystal. Therefore, quasicrystals and B2-based approximants belong to o ne group of phases whose surface properties are mainly determined by electr onic structure characteristics rather than crystal structures.