The regularities of the relationship between the anomalies of physicomechanical properties of nonferrous alloys and phase equilibrium diagrams

Abstract

: The existing numerous experimentally-built phase equilibrium diagrams of nonferrous alloys reflect the specific character of interaction of the components at their different ratios and different temperatures and give an idea of the so-called “metallographic” structure of alloys. In general, the literature sources establish a rather good relation between the structu re and the properties, which allows controlling properties, predicting their possible change when varying the components concentrations and the structure forming conditions. However, the applied criteria, which sometimes allow explaining and predicting the level of the achieved properties according to phase equilibrium diagram appearance, do not make it possible to explain the nature of a rather large number of existing anomalies of physicomechanical properties of the industrially used nonferrous alloys. Based on the study of numerous literature data, the author identified the regularity, which allows establishing a relationship between the anomalies in the physicomechanical properties of nonferrous alloys and phase equilibrium diagrams. The author introduced the concept of phase equilibrium diagram as the concentration dependence of the qualitative changes in the crystallization (recrystallization) intervals, which makes it possible to associate the phase equilibrium diagram with the extreme values of physicomechanical properties, which cannot be explained by the peculiarities of the phase composition or structure. The author developed the technique that allows associating anomalies in the properties of alloys with phase equilibrium diagrams based on the first established criterion – a qualitative change (temperature ex-tension) of the cr ystallization (recrystallization) interval (Q∆LS), as well as with a difference in the structural heredity (g e-nealogy) of the component atoms that make up the dual system. The joint analysis of the anomalies in the properties of binary alloys with state di agrams (based on the established criterion (Q∆LS)) allows relating the latter to the presence of intermediate phases in the Cu – Zn, Cu – Sn, Cu – Si, Al –Cu, Al−Si, Al−Mg, Al– Cu – Mg, Cu – Mn systems. Based on the identified regularity of the relationship between the anomalies of physicomechanical properties of alloys and the qualitative changes in the crystallization (recrystallization) interval (Q∆LS), the author proposes an alternative version of Kurnakov’s law.