  In this work, we present the formation and characterization of a quaternary
(pseudo ternary) icosahedral quasicrystal in Al65Ga5Pd17Mn13 alloy. The X ray
diffraction and transmission electron microscopy confirmed the formation of
icosahedral B2 type and O crystalline (orthorhombic structure) phases in as
cast alloy. The icosahedral phase gets formed after annealing at 800 C for 60
hours. The formation of icosahedral phase in AlGaPdMn quaternary alloy by
present technique has been studied for the first time. The Energy dispersive
X-ray analysis investigations suggest the presence of Ga (5 at) in the alloy.
It is interesting to note that pseudo twelve fold pattern in the as cast alloy
has been observed. Icosahedral AlGaPdMn provides a new opportunity to
investigate the various characteristics including surface characteristics.
Attempts will be made to discuss the micromechanisms for the formation of
quasicrystalline phase in Al-Ga-Pd-Mn alloys.
