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Attached hereto are two copies of our First Technical Report on fesk Order Coatraot lo. Sj Contract lo.. Il.~04-200-0EI>-171s entitled *leformation Meehanisas in Polycrystalline Aggregates of lagnesima®« &e sigEdficaat observatloii aade thtis far centers about the low ductility and low fracture strengths of coarse-grained, high-purity aagaesiua. In the fmtsare Inrestigatlons oajor effort will be devoted to elucidating the fracttiring SKchanisms and laws" in polycrystalline aggregates of magnesium and its alloys as Inactions of grain size and temperature* Sincerely yours, JdLlC.fclcAM

BITTER, KAUFMANN, STARR AND PANeach W when Do is in angstroms. Table I also shows a comparison of the results here obtained with those of Bardeen and the image force law.The former values were computed from the relation 7 W=-(e%Ri%/l2D 0 9 )(Ce 2 /2r a hvi/l + Ce i /2rJiv l ) developed by Bardeen, and the latter were obtained from Eq. (1). The agreement with Bardeen's theory appears on the whole satisfactory, although the values obtained from the latter are always lower than ours. Table II contains similar data for divalent metals.I N the first paper of this series 1 the authors described a method of measurement which has been used again for the present experiments. The only difference in this case is that the location of the specimen in the magnet has been changed slightly in order to have stable equilibrium and that the furnace of Fig. 2, Part I, has been replaced by a Dewar flask for low temperature measurements. The specimens were in an atmosphere of hydrogen for all experiments except those below 60°K for which a mixture of hydrogen and helium was used.Some preliminary results presented in Part I on alloys of copper with small percentages of iron showed that the magnetic properties depended in a complicated way on the heat treatment of the 1 F. Bitter and A. Kaufmann, Phys. Rev. 56, 1044 (1939.The interaction between the metal ions and the visiting molecule is of course included in the basic formulas (9) and (11). But the approximations made in evaluating A {2) and AE Av(2) ignore this effect. It is therefore of interest to calculate it separately in order to exhibit its order of magnitude. This was done by the methods of reference 4 for the metal Na only. The interaction energy is also proportional to J9 0~3 ; the coefficient, in the same units as the others, is given in the last column of Table I. Clearly, this effect is generally negligible in comparison with that expressed by Eq. (12).specimens. In an effort to narrow the range of investigation, the present experiments have been confined to that state of the alloys in which all the iron is believed to be in solid solution. This state surely exists in the high temperature measurements above the solubility limits and it is assumed to exist for all the present experiments at room temperature and below because each of the specimens was quenched in water from above the solubility limits.The alloys for this investigation were made by dissolving iron in molten electrolytic copper in an atmosphere of hydrogen and then chill casting in vacuum. The castings were annealed for 5 days at 1000°C and then quenched after which they were swaged to the desired size. Samples for measurement were cut from this stock and prepared by annealing the low iron alloys at 950°C and the JULY 15, 1941 PHYSICAL REVIEW VOLUME 60The alloys of copper and iron which have been studied show unusual magnetic properties both in the saturation effects at low temperatures and in the apparent change in the magnetic moment of the dissolved iron atoms over the range of temperatures from 14°K to ...

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