Effect of the Size of [Al.sub.3] Precipitates on the Structure of Multi-Directionally Isothermally Forged Al-Mg-Sc-Zr Alloy

The effect of [Al.sub.3](Sc,Zr) dispersoids on the evolution of the cast Al-Mg-Sc-Zr alloy structure under multi-directional isothermal forging (MIF) has been investigated. The alloy, which has an equiaxed grain structure with a grain size of ~25 [micro]m and contains dispersoids 5-10 and 20-50 nm i...

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Bibliographic Details
Published in:	Physics of metals and metallography Vol. 118; no. 12; p. 1215
Main Authors:	Sitdikov, O.Sh, Avtokratova, E.V, Mukhametdinova, O.E, Garipova, R.N, Markushev, M.V
Format:	Journal Article
Language:	English
Published:	Springer 01-12-2017
Subjects:	Alloys Annealing Grain boundaries Specialty metals industry Zirconium
Online Access:	Get full text
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Summary:	The effect of [Al.sub.3](Sc,Zr) dispersoids on the evolution of the cast Al-Mg-Sc-Zr alloy structure under multi-directional isothermal forging (MIF) has been investigated. The alloy, which has an equiaxed grain structure with a grain size of ~25 [micro]m and contains dispersoids 5-10 and 20-50 nm in size after one-stage (at 360[degrees]C for 6 h) and two-stage (360[degrees]C for 6 h + 520[degrees]C for 1 h) annealing, respectively, was deformed at 325[degrees]C (~0.65[T.sub.m]) up to cumulative strains of e = 8.4. In the initial stages of MIF, new fine (sub)grains surrounded by low-angle and high-angle boundaries (HABs) were formed near the initial grain boundaries. With increasing strain, the volume fraction and misorientation of these crystallites increased, which led to the replacement of a coarse-grained structure with a fine-grained one with a grain size of ~1.5-2.0 p.m. Dynamic recrystallization occurred in accordance to a continuous mechanism and was controlled by the interaction of lattice dislocations and/or (sub)grain boundaries with dispersoids that effectively inhibited the migration of boundaries, as well as the rearrangement of lattice dislocations and their annihilation. The particle size and the density of their distribution significantly affected the parameters of the evolved structure; in an alloy with smaller particles, a structure with a smaller grain size and a larger HAB fraction developed. Keywords: aluminum alloy, dispersoids, multi-directional isothermal forging, microstructure, continuous dynamic recrystallization DOI: 10.1134/S0031918X17120122
ISSN:	0031-918X
DOI:	10.1134/S0031918X17120122