Structural, tribological and resistivity studies of Ga substituted (Al71−xGax)Pd21Mn8 icosahedral and other intermetallic phases

We report the formation of icosahedral phase in Al71−xGaxPd21Mn8 (x = 0, 4, 6, 8, and 10 at.%) by adopting powder metallurgical route. Such a variation in Ga substitution in the alloy composition gave rise to a nearly single phase face centred icosahedral phase for x = 6. All other Ga substituted compositions displayed formation of intermetallic phases in addition to the icosahedral quasicrystals. The 6d hypercubic lattice parameter for the Ga substituted icosahedral phase is higher than that of Al71Pd21Mn8 composition. The change in the lattice parameter is non-monotonic. Such a change in lattice parameter has been explained based on the mixed valence states of Ga on Al site. The electrical resistivity of x = 6 sample is comparable to those of earlier studies pertaining to flux grown icosahedral composition of Al(Ga)PdMn alloy. Further, x = 6 sample has displayed highest value of static friction coefficient. This has been understood in terms of the shift of Fermi level from the pseudo-gap location owing to mixed valence states of Ga.

► For x = 6, the Ga addition on Al site in (Al71−xGax)Pd21Mn8 system stabilizes nearly single FCI phase.
► The variation of 6d lattice parameter of FCI with respect to Ga addition has been explained.
► The up-turn of resistivity with respect to temperature has been observed.
► The tribological behaviours as well as lower resistivity value has been understood.