S. Delsante , G. Borzone , N. Parodi , S. Guerrucci
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引用次数: 0
Abstract
The present study is devoted to the experimental investigation of homogeneity range and heat of formation (ΔfH° at 300 K) of the cubic L12–HfAl3-xZnx solid solution. A high-temperature direct drop calorimeter has been employed to synthesize and simultaneously determine the ΔfH° of several alloys along the HfZn3–HfAl3 section (25 at. % Hf) whereas X-Ray Powder Diffraction (XRPD) and Scanning Electron Microscopy (SEM) paired with an EDS (Energy Dispersive Spectrometer detector) have been employed to characterize the samples. The performed analysis confirmed that the ternary HfAl3-xZnx alloys were nearly single phase in the range 1 ≤ x ≤ 2.24 having the cubic L12 structure; this in turn helps establish the trend of L12 lattice parameter (at room temperature) with composition. Thanks to the interpolation of our experimental data, the following values of ΔfH° (kJ/mol-atom at 300 K) for the L12–HfAl3-xZnx were determined: -37.1 ± 2.0 (HfAl0.8Zn2.2 corresponding to Hf25Al20Zn55 at. %), -41.7 ± 2.0 (HfAl1.2Zn1.8 corresponding to Hf25Al30.0Zn45.0 at. %), -45.1 ± 2.0 (HfAl1.5Zn1.5 corresponding to Hf25Al37.5Zn37.5 at. %) and -48.5 ± 2.0 (HfAl1.8Zn1.2 corresponding to Hf25Al45.0Zn30.0 at. %). For two pertinent binary intermetallic phases, the following ΔfH° values (in kJ/mol-atom) at 300 K have been obtained: -31.8 ± 3.0 for HfZn3 (unknown structure) and -37.0 ± 2.0 for HfAl3 (tetragonal DO23 – type structure).
期刊介绍:
Thermochimica Acta publishes original research contributions covering all aspects of thermoanalytical and calorimetric methods and their application to experimental chemistry, physics, biology and engineering. The journal aims to span the whole range from fundamental research to practical application.
The journal focuses on the research that advances physical and analytical science of thermal phenomena. Therefore, the manuscripts are expected to provide important insights into the thermal phenomena studied or to propose significant improvements of analytical or computational techniques employed in thermal studies. Manuscripts that report the results of routine thermal measurements are not suitable for publication in Thermochimica Acta.
The journal particularly welcomes papers from newly emerging areas as well as from the traditional strength areas:
- New and improved instrumentation and methods
- Thermal properties and behavior of materials
- Kinetics of thermally stimulated processes