Study of imperfections in iron whiskers

Abstract

Iron whiskers grown by hydrogen reduction of ferrous chloride were studied by several X-ray and optical techniques, particularly by X-ray diffraction topography. 36 whiskers with [loo], [ l l O ] and [ l l l ] axis directions, from 20 prn to 260 p m in thickness were investigated. They were of different degree of perfection with dislocations nonuniformly distributed. Three [111] whiskers showed a lattice twist around the axis. Burgers vectors of several frequent types of dislocations were found. Bei Reduktion von Eisenchlorid mit Wasserstoff gewachsene Eisen-Fadenkristalle wurdeii mit Hilfe verschiedener rontgenographischer und optischer Alethoden, besonders init der Rontgenbeugungstopographie, studiert. 36 Whisker mit den Achsenrichtungen [loo], [110] und [ l l l ] und 20 pm bis 260 pm dick legen vor. Sie besaI3en verschiedene Perfektion mit ungleichiniiBig verteilten Versetzungen. I n drei [ 11 I]-Whiskern wurde eine Gitterverdrehung urn die Achse beobachtet. Die Burgersvektoren von einigen hiiufiger vorkoxnmenden Versetzungst,ypen wurden hestimmt.KITAl) and by X-ray topography (KUSHNIR, SIDOKHIN ; NAGAKURA, CHIKAURA ; CHIKAURA, NAGAKURA). Whiskers of different quality were investigated ranging froin the perfect ones to those containing low angle boundaries. A uniform lattice t w i s t corresponding to an axial screw dislocation with Burgers vector of 12.6 A was found by KITAI. No such dislocation was observed, however, by X-ray topography.NAGAKURA and CHIKAURA obtained very perfect whiskers by annealing them after the growth for 20 hours a t 800 "C. Those whiskers showed lattice distortion around the edges and at the roots of branches which the authors explained by the segregation of impurities. KUEHNIR and SIDOKHIN stated that the shape irregularities are connected