Microbands in 80% Drawn Copper Single Crystals With and Starting Orientations

Copper single crystals with the starting orientations <111> and <100> were drawn 80%. In the core region of the rods the orientations and the microstructures were investigated. The stable <111> crystal had a structure consisting of equiaxed cells and microbands which were formed parallel to the {111} planes with the exception of the {111} plane in the cross section of the rod. The <100> orientation was not entirely stable; the beginning of some orientational changes was observed at a high degree of deformation. In the parts with stable orientation a cylindrical cell structure was found with the long axes parallel to the drawing direction. Single microbands formed locally. Dislocation tangles around them finally developed, which lead to a change of the <100> orientation.

The Structure Effect on Selective Growth in Recrystallization

The effect of the dependence of grain boundary mobility on misorientation angle and that of structure of the matrix on the growth selectivity during primary and secondary recrystallization are discussed. It was found that the longer is the distance travelled by the growing grain boundaries and the wider the range of the misorientation angles between the new grains and the matrix, the less is the difference between the grain boundary mobilities of the growing grains, necessary for the manifestation of growth selectivity. So during secondary recrystallization the latter is more manifest. In primary recrystallization after moderate deformations, the growth selectivity will be the least obvious when the deformed matrix consists of small differently oriented areas at whose borders new grains nucleate simultaneously. The secondary grain boundaries should be characterized by “effective” mobility, which depends on the number of the adjacent grains and their dimensions, as well as on the growing grain misorientation in relation to these grains. In the small grained material without a texture, the effective boundary mobilities of any grains are equal, and so the growth selectivity in such a material is non-existing.

Oriented Nucleation in the Reverse Transformation of Fe-30 Ni

Reverse transformation of different martensite textures has been investigated. Starting with austenite the martensite was produced by rolling, deep cooling, or by a combined treatment. In most cases, during the reverse transformation the reconstitution of the original austenite texture occurred. This is explained by oriented nucleation of residual austenite during reverse transformation.

Program for Calculation of Augmented Jacobi Polynomials

The augmented Jacobi polynomials, designated Zℓmn by Roe, or the closely related generalized Legendre functions, Pℓmn(cos⁡ϕ) of Bunge, are required for series expansions of the crystallite orientation distribution. The problem of publishing extensive tabular information has limited compilation of these functions to certain crystal and physical symmetries. This paper gives a brief description and listing of a computer program which permits calculation of Fourier sine (m–n odd) or cosine (m–n even) series expansions of Zℓmn(ξ) for ℓ=0,1,…,32; m=0,1,…,ℓ; n=0,1,…,ℓ.

Texture Control and the Drawability of α-Brass

Texture strengthening analyses for cubic metals predict enhanced deep drawing performance with {110} and/or {111} components in the plane of the sheet. Since {110}<112> is the primary texture in heavily cold rolled α-brass, an attempt was made to retain this texture through recovery of the cold rolled material at low temperatures. A second approach is suggested by the observation of the {110} texture in α-brass on annealing ≳600°C (873°K), and involves short time exposures to limit grain size. It is found that low temperature recovery treatments, while partially retaining the rolling texture, produce a hard condition of low drawability. High temperature annealing produces appreciable {110} textural components only at grain sizes too large for many commercial applications. A potentially more tractable approach is discussed.

The Problem of Texture in Mössbauer Spectroscopy

In Mössbauer spectroscopy it is desirable to work with single crystals or with polycrystalline material of random orientation. The actual, most occuring, case of preferred orientation (texture) and its influence on the relative line intensities of hyperfine split Mössbauer spectra is analysed. Texture information which can be obtained from such an analysis is demonstrated with variously prepared barium ferrite (Ba Fe12 O19) samples.