Thermal Conductivity of Taylor Phase Al3(Mn,Pd) Complex Metallic Alloys

Thermal conductivity, κ, of Taylor phase T-Al73Mn27–xPdx (x = 0,2,4,6) complex metallic alloys (CMAs) has been studied in the temperature interval from 2 K to 300 K. The characteristics of κ are typical for the CMAs: a relatively small value, a change of slope at about 50 K and an increase of slope above 100 K. The value of κ is between 2.7 W/m K and 3.7 W/m K at room temperature. The low thermal conductivity has it’s origin in a complex structure: aperiodic on a short length scale, which leads to frequent electron scattering (i.e. to a low electronic contribution to the thermal conductivity), while the large lattice constant defines a small Brillouin zone that enhances umklapp scattering of extended phonons. Above 100 K the non-extended (localized) lattice vibrations are thermally excited, and hopping gives a new heat carrying channel resulting in typical increase of the thermal conductivity with temperature.