Diffusion Along Migrating and Stationary Grain Boundaries: The Al-Zn System

1982 ◽  
Vol 21 ◽  
Author(s):  
W. Gust ◽  
M.B. Hintz ◽  
R. LuČić ◽  
B. PREDEL
Keyword(s):  
Solid Solution ◽  
Grain Boundaries ◽  
Discontinuous Precipitation ◽  
Eutectoid Reaction ◽  
Precipitation Reaction ◽  
Discontinuous Precipitation Reaction ◽  
Order Of Magnitude ◽  
Diffusion Rates ◽  
Discontinuous Coarsening ◽  
Zn Alloy

ABSTRACTThe discontinuous precipitation reaction has been studied in an Al-28a/o Zn solid solution. It appears that the diffusion rates determined by us for migrating grain boundaries are of the same order of magnitude as the values determined by Häβner (1974) for stationary grain boundaries. To the same statement have led results from the discontinuous coarsening reaction in an Al-29a/o Zn alloy (Fournelle et al., 1982) as well as from the eutectoid reaction in an Al-60a/o Zn alloy (Cheetham et al., 1971).

scholarly journals Discontinuous Dissolution Reaction in a Fe-13.5 at. % Zn Alloy

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1939
Author(s):  
Paweł Zięba ◽  
Mateusz Chronowski ◽  
Jarosław Opara ◽  
Olga A. Kogtenkova ◽  
Boris B. Straumal
Keyword(s):  
Solid Solution ◽  
Reaction Front ◽  
Discontinuous Precipitation ◽  
Precipitation Reaction ◽  
Transmission Electron ◽  
Discontinuous Precipitation Reaction ◽  
Zn Concentration ◽  
Zn Content ◽  
Discontinuous Mode ◽  
Zn Alloy

The dissolution process of a lamellar structure with α and Γ phases formed during a discontinuous precipitation reaction is investigated here with a Fe-13.5 at. % Zn alloy by means of optical microscopy and scanning and transmission electron microscopy. The α phase is a solute-depleted solid solution and the Γ phase is the intermetallic compound Fe3Zn10. The examination reveals that the dissolution occurs in a discontinuous mode by a receding of the former reaction front of the discontinuous precipitation towards the position of the original grain boundary. A new solid solution in the post-dissolution area is especially inhomogeneous and reflects the former locations of the Γ lamellae (“ghost images”) and the receding reaction front (“ghost lines”). A simulation procedure is applied to determine the Zn concentration profiles left in the post-dissolution region. Their shapes are mostly affected by the Zn content at the positions where the Γ lamellae have just been dissolved, which was also confirmed by the quantitative microchemical analysis.

Phase Transformations and Ageing Phenomena in Copper-Nickel-Manganese Alloys

1982 ◽  
Vol 21 ◽  
Author(s):  
A.E. Weatherill ◽  
R.A. Buckley
Keyword(s):  
Grain Boundaries ◽  
Discontinuous Precipitation ◽  
Alloy System ◽  
Precipitation Reaction ◽  
Heterogeneous Precipitation ◽  
Manganese Alloys ◽  
Discontinuous Precipitation Reaction ◽  
The Subject ◽  
Binary Alloy System ◽  
Nickel Manganese

The pseudo-binary alloy system extending between copper and the intermetallic NiMn was first shown by Dean et al. [1,2] to yield a series of age hardenable alloys. The alloy containing 20% each of Ni and Mn has the best combination of strength and toughness and has been the subject of more recent studies [3,4]. The phase transformation associated with ageing in quenched Cu-NiMn alloys is precipitation of the ordered tetragonal (Llo) phase, (⊖) based on NiMn, from an fcc solid solution. Generally three modes of transformation occur depending on composition and temperature. An intragranular precipitate of fine coherent particles of ⊖, or a cellular or discontinuous precipitation reaction emanating from the grain boundaries, or heterogeneous precipitation of ⊖ at the grain boundaries.

Sign in / Sign up

Export Citation Format

Share Document