Änderung von Verformungseigenschaften der intermetallischen Verbindung MgZn₂ im Homogenitätsbereich

Abstract

Der im Homogenitätsbereich der intermetallischen Verbindung MgZn2 beobachtete Effekt der Legierungsentfestigung erweist sich nach Vergleich mit Messungen der Versetzungsgeschwindigkeit und der Versetzungsdichte als durch Versetzungsdichteänderung hervorgerufen.

Yield strength of the monocrystalline intermetallic compound MgZn2

“…The solid solution softening observed within the range of homogeneity of the interinetallic compound is in accordance with the results of creep tests and measurements of the micro-hardness (see, e.g., [4]) and has been correlated earlier [2] with a higher dislocation density when the chemial composition differs from czn = 2/3 (see also [4]). The occurrence of plastic instabilities in crystals with nearly stoichiometric composition (that means in crystals with a minimum of initial dislocation density) supports the assumption of the dominating influence of the dislocation multiplication on the initial deformation curve.…”

Early work on Laves phases in East Germany

“…One is along the line of measuring dislocation velocity v and density r d via etch pit dynamics [103,115,116,127e132]. One of the key findings during this work was an etchant for dislocations [54,103,108,115,128,133]. It enabled the local variation of the density as well as the velocity of dislocations to be determined (Fig.…”

“…Unlike a naive expectation, hardness at the off-stoichiometric compound proved lower than at the stoichiometric composition. The salient point seems the increase of grown-in dislocation density overcompensating the reduced dislocation velocity [65,66,96,108,116,117,120,121,136]. In eq.…”

“…14b, softening also showed up with the stationary creep velocity c at 350 C under shear stress 10 MPa as an example. While the average dislocation velocity v slowed down due to off-stoichiometry, the total dislocation density d increased (data from [108,136] Boiling macroscopic mechanics down to microscopic dislocation behaviour [125] was accomplished exploiting Orowan's equation [126] de pl =dt ¼ kbr d ðsÞvðs; TÞ;…”