THE ALUMINUM PALLADIUM MANGANESE SYSTEM IN THE RANGE FROM 60 TO 100 AT-PERCENT AL

The constitution of the ternary Al-Pd-Mn system was investigated in th e Al-rich region up to 60 at.% Al. Differential thermoanalysis, magnet othermal analysis, optical microscopy, scanning electron microscopy an d EDX analysis were applied. 70 samples of different compositions were prepared. The AlMn, AlPd, and PdMn phases with cubic structures form a solid solution in the ternary. Two ternary phases with decagonal and icosahedral structure are formed by ternary peritectic reactions. Due to sluggish reaction the formation of the decagonal phase from the me lt is suppressed. A liquidus surface projection of the stable diagram has been determined from heating experiments. In the stable and in the metastable system ten and nine surfaces of primary crystallization ha ve been derived, respectively. Twelve and eleven four-phase planes are deduced for the stable and the metastable diagram, respectively. The liquidus surface projection and three isothermal and four temperature- composition sections have been elaborated in detail. The Scheil reacti on scheme is reported. In addition, a transition of modification was f ound at 864-degrees-C in the decagonal phase. Etch pits with polyhedra l shapes bounded by pentagons as well as with decagons and triangles c onfirmed the icosahedral structure.