Recovery recrystallization

Figure 5.18 Influence of annealing temperature on tensile strength and ductility of a brass alloy. Grain structures during recovery, recrystallization, and grain growth are shown schematically. Reprinted, by permission, from W. Callister, Materials Science and Engineering An Introduction, 5th ed., p. 175. Copyright 2000 by John WUey Sons, Inc.

Byrne, J. G. 1965, Recovery, Recrystallization and Grain Growth, Macmillan. 

C. J. McMahon, Jr and C. D. Graham, Jr, published by C. J. McMahon, Jr, 1994 (available from author http //www.seas.upenn.edu/mse/fac/mcmahon.html). This is one of my favorite books. Despite the claimed low level of the book, the discussion of recovery, recrystallization and grain growth is highly instructive as are many other topics covered by the authors. 

Figures 3.1-57a and 3.1-57b show typical softening curves for aluminium alloys in three characteristic stages recovery, recrystallization, and grain-growth. In the case of the untreated continuously cast and rolled strip shown in Fig. 3.1-57a, recrystallization will occur at temperatures between about 260 and 290 °C. In Fig. 3.1-57b, recrystallization starts after about half an hour and is complete after about an hour. The...

The hot-deformation model is required to predict the austenitic microstructure before transformation through recovery, recrystallization, and grain growth in austenitic phase region during and after multipass hot deformation. 

Sellars and Whiteman [78] made the first attempt on this issue and then several researchers [79-80] developed models to calculate recovery, recrystallization, and... 

Frequently the recrystallized azobenzeno has m.p. 61°, which is unaffected by recrystallisation from alcohol. Upon distillation from a. 50 ml. distilling flask fitted with a short air condenser, the m.p. is raised to 67-5° and the recovery is about 90 per cent. one recrystallisation from diluted alcohol (as above) then gives perfectly pure azobenzene of m.p. 68-5°. 

The oxidation reactor effluent and methanol ate sent to the esterification reactor, which operates at up to 250°C and a pressure sufficient to maintain the Hquid phase. This latter is about 2500 kPa (25 atm). The oxidation products are converted to methyl -toluate and dimethyl terephthalate without a catalyst. Excess methanol is suppHed, and steam and vaporized methanol ate removed and enter a methanol recovery column. The esterification products flow to a cmde ester column, which separates the toluate from the terephthalate. The overhead stream of methyl -toluate is returned to the oxidation reactor, and the bottoms stream of dimethyl terephthalate goes to a primary distillation. The distillate is dissolved in methanol, crystallized, and sohd dimethyl terephthalate is recovered. The dimethyl terephthalate can then be either recrystallized or distilled to yield the highly pure material needed for the polyesterification reaction. 

Selenium is added up to 0.1% to silicon steels (2—4% Si) used in transformer cores to enhance the development of the secondary recrystallization texture which, in turn, improves the magnetic characteristics. Selenium alloying additions to the melt may be made as elemental Se, nickel—selenium, or ferroselenium. The recovery depends on the melting practice and method of addition. Normally, it is in the range of 66%, but may be as high as 90%. 

Recovery Process. The process for making sodium sulfate [7757-82-6] is different at each faciUty extracting it from brine. One step common to all facihties is a cooling step to form Glauber s salt followed by a purification and recrystallization step to form anhydrous sodium sulfate. 

The mother liquors from the original cr3 Stallization and recrystallizations are treated in a similar manner and the sodium malate solutions are united and reserved for the recovery of i-malic acid (Note 7). The recovered amine amounts to 75-80 g. and contains 40-50 per cent excess /-amine. 

The diethyl acetamidomalonate obtained is of high purity. If a product of inferior quality is obtained, it may be recrystallized from hot water, using 2.5 cc. per g. Upon cooling, the product separates first as an oil. With rapid stirring, it is converted to fine white crystals which are easily washed with cold water. Diethyl acetamidomalonate may be recrystallized in this manner with 97% recovery. The first crop amounts to 91% and the mother liquors may be concentrated to yield an additional 6%. 

Recrystallization from 75 ml. of 60% ethanol gives a 90% recovery of colorless long needles, m.p. 83-85°. 

This product can be recrystallized by dissolving 10 g. in 20 ml. of hot ethyl alcohol (95%), adding 14 ml. of water, and allowing the solution to cool slowly so that no oiling out takes place. Colorless needles, m.p. 183-185°, [o ] —211 to —217° (in ale.) (Note 6), are obtained (first crop, 7.5-8.5 g., 83-90% recovery further quantities can be recovered from the mother liquor) (Note 7). 

The checkers carried out this recrystallization by dissolving triphenylene in a minimum of methylene chloride maintained at reflux. Pentane was slowly added to this solution up to 90% recovery was achieved. 

In one of the most significant observations, small amounts of recrystallized material were observed in rutile at shock pressure of 16 GPa and 500 °C. Earlier studies in which shock-modified rutile were annealed showed that recovery was preferred to recrystallization. Such recrystallization is characteristic of heavily deformed ceramics. There has been speculation that, as the dislocation density increases, amorphous materials would be produced by shock deformation. Apparently, the behavior actually observed is that of recrystallization there is no evidence in any of the work for the formation of amorphous materials due to shock modification. Similar recrystallization behavior has also been observed in shock-modified zirconia. 

When inserted into an oil bath at 200°, the compound undergoes an immediate change in crystal structure and melts at 232-234°. The mother liquor affords two further crops, mp 228-230° and 227-228.5°, amounting to 3.5 and 10.6 g, respectively. Further recrystallization of the first crop from the same solvent pair raises the mp to 244-245° (70% recovery). 

A solution of 10 g (0.023 mole) of cholesteryl acetate (mp 112-114°) in ether (50 ml) is mixed with a solution containing 8.4 g (0.046 mole) of monoperphthalic acid (Chapter 17, Section II) in 250 ml of ether. The solution is maintained at reflux for 6 hours, following which the solvent is removed by distillation (steam bath). The residue is dried under vacuum and digested with 250 ml of dry chloroform. Filtration of the mixture gives 6.7 g of phthalic acid (87% recovery). The solvent is evaporated from the filtrate under reduced pressure and the residue is crystallized from 30 ml of methanol, giving 6.0 g (58% yield) of -cholesteryl oxide acetate. Recrystallization affords the pure product, mp 111-112°. Concentration of the filtrate yields 1.55 g (15% yield) of a-cholesteryl oxide acetate which has a mp of 101-103° after crystallization from ethanol. 

A 100-ml flask is charged with 25 ml of bromine and 10 g of adamantane and heated under reflux for 3 hours. The cooled mixture is dissolved in 100 ml of carbon tetrachloride, and the carbon tetrachloride solution is washed with 100-ml portions of saturated bisulfite solution until the color of bromine is discharged. The solution is then washed twice with water and dried (magnesium sulfate). The solvent is removed (rotary evaporator) and the product is recrystallized from methanol. (For best recovery of the recrystallized material, the methanol solution should be cooled in a Dry Ice cooling bath.) The product has mp 108°. 

It is not necessary that the intermediate be separated from the reaction medium in the preparation of the end product. Instead, the reaction mixture, after cooling, is treated with 200 ml of water acidified with 42 ml 10% hydrochloric acid solution, and filtered. To the clear, light yellow filtrate is added dropwise a solution of 9.B g (0.07 mol) 5-nltro-2-furaldehyde in 100 ml ethyl alcohol. An orange solution of the hydrochloride results. The free base is precipitated asyellow plates by making the solution basic with saturated sodium carbonate solution. 14 g of the compound is filtered off by suction, washed with alcohol, and dried. The yield, MP 204°C to 205°C (dec.), is 53% of theoretical based on 3-(N-morpholinyl)-1,2-epoxy-propane. Recrystallization from 95% alcohol (75% recovery) raises the melting point to 206°C (dec.). 

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