The alloy world could be divided into low-entropy (LEAs), medium-entropy (MEAs) and high-entropy alloys (HEAs) based on the configurational entropy at the random solution state. In HEAs, four core effects, i.e. high entropy, sluggish diffusion, severe lattice distortion and cocktail effects, are much more significant than low-entropy alloys in affecting phase transformation, microstructure and properties. In fact, the degree of the influence from these core effects more or less increases with increased mixing entropy. The trend is gradual from low-entropy alloys to high-entropy alloys. In this article, physical metallurgy of HEAs is discussed with the bridge connected to that of conventional alloys. As disordered and ordered solid solutions are the main constituent phases of alloys, the understanding of solid solutions is fundamental for the understanding of alloys. In addition, as dilute solid solutions have been well treated in current physical metallurgy, concentrated solid solutions from low-entropy to high-entropy alloys are focused in this article. Physical properties are especially emphasized besides mechanical properties.

Physical metallurgy of concentrated solid solutions from low-entropy to high-entropy alloys

This study is a fundamental investigation aimed at developing a new noncontact modulated laser calorimetry method incorporating a static magnetic field to achieve measurement of the true thermal conductivity of a metallic melt. For establishing the experimental principle, a solid platinum sphere was used in this study. The sphere positioned in the centre of a radio frequency coil was heated sinusoidally by a laser; its temperature response was monitored. Analyses of the temperature amplitude and phase difference between the laser input and temperature response yielded the heat capacity, thermal conductivity and hemispherical total emissivity of platinum for temperatures of 1400–1700 K. The obtained data agree with the reference data within experimental uncertainty, which verifies the experimental method.

http://iopscience.iop.org/article/10.1088/0957-0233/18/7/036/pdf

Development of modulated laser calorimetry using a solid platinum sphere as a reference

The aim of this article is to present an introductory review of those aspects of the isothermal galvanomagnetic effects in metals (which here means the electrical resistance, magnetoresistance and Hall effect) which are peculiar to the existence of an anisotropic electrical conductivity. This anisotropy may be intrinsic to the solid, such as that arising from a non-cubic crystal structure, or it may be induced by the application of the external magnetic field. Such induced anisotropy can itself be divided into two classes : that arising directly from the effect of the Lorentz force upon the itinerant electrons, and that in which the external field is merely an agent which makes evident on a macroscopic scale an anisotropy which exists microscopically, even in the field-free case. The article traces the usual phenomenological formulation of the galvanomagnetic effects, and then particularizes this to the commonly-encountered experimental situations used to study the consequences of both induced an...

Galvanomagnetic effects in anisotropic metals

The spin-dependent coupling between electrons and phonons in ferromagnetic Fe and Co is calculated from first principles in a collinear-spin formalism. The added spin polarization is fundamental for the correct representation of the phonons, but also for obtaining good transport properties, and permits decomposition (e.g. of the resistivity) into the contributions of majority and minority spin. In Fe the minority spin coupling is only about 50% more important, but in Co the coupling between phonons and minority spin electrons is an order of magnitude larger than that with the majority spin, and both are strongly anisotropic.

https://iopscience.iop.org/article/10.1088/0953-8984/25/13/136001/pdf

Ab initio calculation of spin-dependent electron-phonon coupling in iron and cobalt.

The thermophysical properties of several hafnium samples with a content of zirconium below 1% were experimentally studied over a wide temperature range. The specific heat capacity and specific electrical resistivity were measured from 300 to 2340 K, the hemispherical total emissivity from 1000 to 2130 K, while the thermal diffusivity was measured in the range from 300 to 1470 K. The thermal conductivity and Lorentz number were computed from measured properties for the range from 300 to 1470 K. The specific heat capacity, specific electrical resistivity, and hemispherical total emissivity were measured by subsecond pulse calorimetry, and the thermal diffusivity using the laser flash method. Samples in the form of a thin rod or wire, and in the form of a thin disk were used in the first and second methods, respectively. For data reduction and computation of relevant parameters, recent literature values of the linear thermal expansion were used. The results are compared with literature data and discussed.

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Thermophysical Properties of Solid Phase Hafnium at High Temperatures

Using the modified Jain and Krishnan method, the thermal conductivity of zirconium has been measured in the temperature range 1100-1500 K. The thermal conductivity of zirconium is found to increase with temperature. Also, the electrical resistivity of zirconium and the total emissivity of ZrO have been measured in the temperature range 1050-1500 K and are reported in this paper.

https://iopscience.iop.org/article/10.1088/0022-3727/1/5/305/pdf

Vijaya Sinha

Papers

Thermal conductivity of metals at high temperatures by the Jain and Krishnan method: V. Zirconium