Correlation between resistivity increment and volume fraction of G.P. zones in an Al-3·2 wt % Zn-2·2 wt % Mg alloy

1980

Cryst Res and Technol

The experimentally gained course of the resistivity of some Al-Zn-Mg alloys during isothermal aging is analyzed by means of a calculation of the extra resistivity of GUINIER-PRESTON zones based on the solution of the BOLTZMANN-equation in the isotropic relaxation time approximation and using XSAS intensities quoted by GUINIER and FOURNET.Applying this equation from the increase of the resistivity information on the time development of the volume fraction of the zones and from the course of the resistivity behind the maximum the growth law of the precipitates can be drawn from the alloys investigated.Die Verlaufe experimenteller Widerstandskurven, gemessen an isotherm im RT-Bereich gealterter AIZnMg-Legierungen, wurde mit Hilfe des berechneten Zusatzwiderstandes von GUINIER-PRESTON-Zonen a-nalysiert. Die Rechnungen basieren auf einer Losung der BOLTZMANN-Gleichung in der isotropen Relaxationszeit-Naherung und auf der Verwendung theoretisch von GUINIER und FOURNET berechneter Intensitaten der RKWS. -Unter Verwendung dieser Gleichung konnen aus dem anfiinglichen Widerstandsanstieg Informationen uber die zeitliche Entwicklung des Volumenanteils der Zonen und vom Verlauf des Widerstandes nach dem Maximum das Wachstumsgesetz der Zonen gewonnen werden.

Information gain from analytical description of isothermal resistivity curves

Oettel

1980

Cryst Res and Technol

On the relation between X-ray small-angle scattering and electrical resistivity

1978

Phys. Stat. Sol. (a)

A relation between XSAS intensity spectra and electrical resistivity is developed assuming that Ziman's equation holds and the mean value of the square of the Fourier transform of the total scattering potential of the conductivity electrons on the lattice points is proportional to the intensity of the scattered X‐rays as sometimes used for fluids. In the first step this model is extended to pure metals in the solid state (supposing that the Bragg peaks of an ideal lattice do not contribute to resistivity) and transformed from a relation of proportionality into an equation. In the frame of this model the resistivity is proportional n0–8/3 (where n0 the mean value of conductivity electron density). The further considerations show that the formulae valid for pure metals can be extended very easily to multinary alloys replacing n0, pure by n0, alloy = \documentclass{article}\pagestyle{empty}\begin{document}$ \sum\limits_{i = 1}^k {c_i n_0,i}. $\end{document} cin0, i. A first rough comparison of the calculated and experimentally measured resistivities yields the right order of magnitude of the contribution of the GPZ zones to the resistivity.

On the Extra-Resistivity of Coherent Precipitates

1979

Phys. Stat. Sol. (a)

By means of a formula recently developed by the authors which allows one to calculate the extra‐resistivity of GP zones (Δϱex) by the help of theoretical XSAS intensities and XSAS intensity distribution functions of single spherical as well as ellipsoidal GP zones the course of Δϱex is calculated considering certain decomposition processes. For example it is shown that the shape of the zones is remarkably affecting Δϱex. This conclusion is supported by experimental investigations performed on an AlZn(6 at%)Mg(0.1 at%) alloy. Under special conditions Δϱex ∼ f2/3 (f volume fraction of the zones) holds in accordance with experimental results of some other authors.