The Effect of Cold Work on the Precipitation and Recrystallization Kinetics in Al-Sc-Zr Alloys

ABSTRACTThe recrystallization kinetics, structure development, stored energy of cold work, and rolling and recrystallization textures were studied on boron doped Ni76Al24. The recrystallization kinetics were very slow compared to pure metals or disordered solid solutions, but similar to other intermetallic compounds. The development of the deformed and recrystallized microstructure is similar to metals with intermediate stacking fault energy. Despite a lack of massive deformation twinning the rolling texture is a typical brass type texture. The recrystallization texture is not a brass type recrystallization texture, but consists of components, which are related by a 25°<100> rotation among each other and with the deformation texture. The observed phenomena are attributed to the constraints of grain boundary motion in long range ordered structures. It is further shown that Ni3Al does undergo dynamic recrystallization during high temperature deformation.

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The Influence of Grain Boundaries on the Stored Energy of Cold-Work and Recrystallization Kinetics

Materials Science Forum ◽

10.4028/www.scientific.net/msf.207-209.521 ◽

1996 ◽

Vol 207-209 ◽

pp. 521-524 ◽

Cited By ~ 5

Author(s):

D. Mandal ◽

Ian Baker

Keyword(s):

Grain Boundaries ◽

Cold Work ◽

Stored Energy ◽

Recrystallization Kinetics

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Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071363 ◽

1973 ◽

Vol 31 ◽

pp. 184-185

Author(s):

M.S. Grewal ◽

S.A. Sastri ◽

N.J. Grant

Keyword(s):

High Temperature ◽

Nickel Alloys ◽

Thermomechanical Processing ◽

Cold Work ◽

High Temperature Strength ◽

Strengthening Effect ◽

Mechanical Processing ◽

Uniform Dispersion ◽

Oxide Particles ◽

Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

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In situ investigation of the primary recrystallization of alpha titanium in HVEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100110313 ◽

1978 ◽

Vol 36 (1) ◽

pp. 634-635

Author(s):

S. Naka ◽

R. Penelle ◽

R. Valle

Keyword(s):

Dimensional Analysis ◽

Texture Evolution ◽

Cold Work ◽

Three Dimensional ◽

Primary Recrystallization ◽

Thin Foils ◽

In Situ Investigation ◽

Grain Growth Model ◽

Alpha Titanium

The in situ experimentation technique in HVEM seems to be particularly suitable to clarify the processes involved in recrystallization. The material under investigation was unidirectionally cold-rolled titanium of commercial purity. The problem was approached in two different ways. The three-dimensional analysis of textures was used to describe the texture evolution during the primary recrystallization. Observations of bulk-annealed specimens or thin foils annealed in the microscope were also made in order to provide information concerning the mechanisms involved in the formation of new grains. In contrast to the already published work on titanium, this investigation takes into consideration different values of the cold-work ratio, the temperature and the annealing time.Two different models are commonly used to explain the recrystallization textures i.e. the selective grain growth model (Beck) or the oriented nucleation model (Burgers). The three-dimensional analysis of both the rolling and recrystallization textures was performed to identify the mechanismsl involved in the recrystallization of titanium.

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Precipitation in Al-Li-Zr alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121338 ◽

1992 ◽

Vol 50 (1) ◽

pp. 186-187

Author(s):

D.M. Vanderwalker

Keyword(s):

Fracture Toughness ◽

Precipitation Hardening ◽

Weight Ratio ◽

High Strength ◽

Transmission Electron ◽

Water Quench ◽

Aluminum Lithium ◽

Aluminum Lithium Alloys ◽

Lithium Alloys ◽

Zr Alloys

Aluminum-lithium alloys have a low density and high strength to weight ratio. They are being developed for the aerospace industry.The high strength of Al-Li can be attributed to precipitation hardening. Unfortunately when aged, Al-Li aquires a low ductility and fracture toughness. The precipitate in Al-Li is part of a sequence SSSS → Al3Li → AlLi A description of the phases may be found in reference 1 . This paper is primarily concerned with the Al3Li phase. The addition of Zr to Al-Li is being explored to find the optimum in properties. Zirconium improves fracture toughness and inhibits recrystallization. This study is a comparision between two Al-Li-Zr alloys differing in Zr concentration.Al-2.99Li-0.17Zr(alloy A) and Al-2.99Li-0.67Zr (alloy B) were solutionized for one hour at 500oc followed by a water quench. The specimens were then aged at 150°C for 16 or 40 hours. The foils were punched into 3mm discs. The specimens were electropolished with a 1/3 nitric acid 2/3 methanol solution. The transmission electron microscopy was conducted on the JEM 200CX microscope.

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