Figure 1. Partial X-ray and neutron diffraction patterns for a two-phase measured for these types of alloys. In figure 2 are shown pole-figure patterns for one matrix-phase and two tungsten-phase reflections. The three sets of pole figures correspond to cylindrical samples which have been cold-worked by "upsetting" with an 8% increase in cross-section (5904B), and swaged with an 8% decrease in cross-section (5903B and 5905J). Cold-working of the latter pair was performed at two different fabrication facilities. As one would expect, the fiber textures of the "upset" and swaged samples are different. On the other hand, the pattern of sample 5903B is essentially untextured whereas that of 5905J shows definite texture in the tungsten phase for nominally, the same cold-working. The matrix phase (111) pattern shows little if any clear texture. In contrast to the above results, samples which have been swaged to a 16% reduction in area show very pronounced tungsten and matrix phase textures. As shown in figure 3, the matrix-phase (111) pattern exhibits a more pronounced fiber texture than the tungsten-phase (110) pattern. Figure 2. Ni(111) Neutron diffraction pole figures for three of the tungstenand matrix-phase reflections shown in Figure 1. The samples were 0.7 cm diameter cylinders, approximately 10 cm in length. The center of each figure corresponds to a configuration in which the scattering vector is aligned with the cylinder axis. Fabrication of the three samples is described in the text. Figure 3. Tungsten-phase (110) and matrix-phase (111) textures for a 16% R.A. swaged sample. In this case the data were obtained at the center-line of a piece cut from a full-scale (~3 cm diameter) production-type sample. In summary, the neutron diffraction study of texture in these samples reveals some differences resulting from cold-working that would not have been observable with x-ray diffraction alone. Although the significance of the measurements as they relate to ductility, hardness, etc. is not determined, it is clear that the nondestructive nature of the neutron probe allows empirical correlations to be made between measured properties and performance. 1. 2. C. S. Choi et al., NBS Tech. Note 995, p. 34 (1979), and references cited. C. S. Choi, H. J. Prask and S. F. Trevino, J. Appl. Cryst., 12, 327, (1979). ACTIVATION ANALYSIS: SUMMARY OF 1979 ACTIVITIES Rolf Zeisler As part of the Inorganic Analytical Research Division, Center for Analytical Chemistry, the Activation Analysis Group is physically located in the NBS-Reactor building. It has at present a staff of 7 full-time members who are conducting research in the development and application of advanced nuclear analysis techniques. The scope of the work is within the following functions of the National Bureau of Standards: aration and distribution of standard reference materials and their use in chemical analysis, and the development of methods of chemical analysis. the prep The Neutron Activation Analysis (NAA) program included numerous measurements at a high level of precision and accuracy in support of the Standard Reference Materials programs which include the certifications of inorganic and organic compounds for the chemical composition (major, minor, and trace elements). The Activation Analysis Group continually develops or modifies new procedures in order to support the SRM certification with improved precision and accuracy. In addition to the lasting support to the NBS Center for Analytical Chemistry, the group has participated in other agency programs and has made significant contributions by developing improved methodology and demonstrating its applications. Such interactions impart the analytical expertise of the group and the NBS to where it is needed. This report summarizes the activities of the Activation Analysis Group during the period of July 1978-June 1979. Included are contributions in the areas of basic research, applied research, certifications, and nonNBS research programs. 1. Basic Research in Nuclear Analysis a. Major Elemental Boron Determination by Nuclear Track Counting J. W. Mitchell and J. E. Riley, Jr. (Bell Laboratories, Murray Hill, NJ) B. S. Carpenter Determinations of boron, when present as a major element (0.5 to 50%), are susceptible to many matrix interferences during chemical analyses. Although most interferences can be eliminated by chemically separating boron as the volatile methyl ester, this procedure requires tedius and time consuming sample processing steps which result in low sample throughout. In contrast, the nondestructive nuclear track counting technique for determining boron is inherently fast and capable of high precision and accuracy. Investigations are now underway to determine the reliability of the method for determining the homogeneity of the distribution of boron in glass and to measure major amounts of this element in optical waveguide materials. 105 2 Reproducible conditions for irradiating samples at the neutron beam tube (flux 3.5 x 10 n/cm sec) have been provided by the sample irradiation chamber shown in figures la and b. The sample (1.27 cm dia disk) is placed between appropriate detector film and clamped securely into holder (A), which is in turn attached to apparatus part (B). After the boral curtain of the reactor is raised, the boral shutter assembly, (C), in the irradiation chamber is used to block the neutron beam. The irradiation chamber lid (D), is then raised, and the assembled sample holder unit (A+B) is then placed on a track which guides it into the irradiation chamber, and reproducibly positions it at the center of the beam part. shutter (C) is raised, held in the beam open position (figure 1b), and lowered at the end of the desired irradiation period. Continuous use of the sample chamber during an eight hour period has resulted in minimal activation of the aluminum-boral chamber parts. The A series of borosilicate glasses of the nominal compositions listed in table 1 have been irradiated. |