Specific heat amorphous alloys

The TCR value of an amorphous alloy strongly correlates with its specific resistance [49]. It also corresponds to the thermal effect on the specific resistance, i.e., the TCR increases at the temperature where the specific resistance abruptly decreases. The TCR values of alloys containing refractory metals exceed those of NiP NiReP alloy film annealed at 500°C in particular has an excellent TCR of 18 ppm K [36]. Although the TCR of as-plated crystalline NiMoP is lower than TCR values of amorphous alloys, heat treatment at 500 C slightly decreases the TCR to 134 ppm , which is a relatively high value, while the value measured after... 

The low-temperature specific heat of icosahedral and amorphous Pd-U-Si alloys was studied by Wosnitza et al. (1988). 

Miscellaneous properties of amorphous alloys are treated in section 9. These comprise properties that have been investigated in only relatively few cases. Examples of such properties are the specific heat, hydrogen absorption, the concentration dependence of the Mbssbauer isomer shift and the few results of ESR on Gd-doped samples. 

Amorphous rare earth base alloys in which the rare earth component carries a magnetic moment contain yet another mechanism which can lead to a linear specific heat contribution. 

A number of specific heat studies was performed on superconducting La-base amorphous alloys. These comprise measurements on amorphous La, j AUj alloys (Shull and Naugle, 1977) and amorphous La, -jGsix alloys (Shull et al., 1978). The results of these studies were discussed in section 8.3. 

A schematic diagram of the measurement is shown in Figure 4.92. An advantage of the enthalpy method is that relaxation of amorphous alloys does not influence the measured specific heat (Cp because the relaxation arises not only during the heating, but also during the thermal arrest. Therefore, relaxation hardly changes C . 

Determination of Specific Heats of Metastable Solids (Nanostructured Crystals, Amorphous Alloys,... 

Fig. 45. Changes in and the difference of the specific heat between amorphous solid and supercooled liquid (ACp sj,) as a function of Ni or Ce concentration for Al-Y-Ni and Al-Ce-Ni amorphous alloys.

The change of the specific heat of the transition from amorphous solid to supereooled liquid as well as the temperature dependence of the specific heat in the amorphous solid and supercooled liquid has been examined for the La-Al-Ni amorphous alloys through detailed differential scanning calorimetric measurements (Inoue et al. 1989f). As an example, fig. 115 shows the thermograms of the amorphous La5sAl25Ni2o alloy with the widest supercooled liquid region. The Cp value of the as-quenched phase is 24 J/mol K... 

The Cp s curve of the reheated (control) sample is unaffected by thermal changes and consists of configurational contributions as well as those arising from purely thermal vibrations. Therefore, the vibrational specific heat, Cp,v, for the amorphous alloy is extrapolated from the Cp values in the low-temperature region and is a linear function of temperature, viz.,... 

Fig. 130. The temperature dependence of apparent specific heat (C, a) of a melt-spun La55Al25Ni2o amorphous alloy annealed for 1.8 ks at different temperatures between 390 and 450 K. The data of the as-quenched (Cp, ) sample and the sample heated for 60 s at 520 K (C s) are also shown for comparison.

Fig. 7. Low temperature specific heat C of two amorphous Zr RhH alloys prepared differently (see subscript Fig. 5). 

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