X-Ray Study of Wire-Drawn Niobium and Tantalum

Abstract

Deformation, introduced into niobium and tantalum specimens by wire drawing at room temperature, produced changes in the shape and position of X-ray diffraction peaks. The resultant peak profiles and locations of all available peaks were recorded using the Debye—Scherrer geometry on a modified diffractometer with crystal monochromated Cu K α1 radiation. The amount of deformation in the surface layers of both metals was’found to saturate essentially after only 20% reduction in area. The measured decrease in the lattice parameters of either material was attributed to a residual surface stress; the average value for the deformed saturated state for both tantalum and niobium wires corresponded to an equivalent longitudinal tensile stress of 35 ± 5 kg/mm2. Integral breadth measurements revealed approximately equal X-ray particle sizes in the ‹100› and ‹110› directions; the minimum particle size for the microstructures of both metals was around 200 Å and occurred after the first few draws.KeywordsResidual StressResidual Surface StressIntegral BreadthWire AxisParticle Size RatioThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.