E. S. Greiner

Observation of Dislocations in V3Si Single Crystals

An etch‐pitting solution which causes etch pits at the point of intersection of dislocations with the (100) and (111) surfaces of V3Si single crystals is described. The effect of second‐phase particles imbedded in the single‐crystal matrix on the density and distribution of the dislocations is discussed. The observation of the dislocation arrangements suggest that the slip system in V3Si is {100} 〈001〉.

ZONE MELTING OF BORON

Compacts of boron powder, suitable for zone melting, were prepared by using boron trioxide as a binder. The powdered crystalline boron was coated by immersing in a boiling aqueous solution of boric acid and evaporating to dryness. A prepared powder compact had satisfactory strength for handling and mounting in a fioating zone melting apparatus. The melted zone, heated with 3.5 megacycle r- f current, was passed toward the bottom end of the compact. It was found that more uniformity of cross section was obtained by moving the zone downward from the top. (A.C.)

Transitions in Chromium

Discontinuous changes of Young’s modulus, internal friction, coefficient of expansion, electrical resistivity, and thermoelectric power are evidence for a transition in chromium near 37°C. Although the X-ray diffraction pattern gives no clue, a difference between the thermal expansivity and the temperature dependence of the lattice parameter suggests a crystallographic change. Young’s modulus data disclosed another transition near—152°C.

Plastic Deformation of Germanium and Silicon by Torsion

Germanium and silicon have been plastically deformed in torsion at elevated temperatures. Slip took place on the four {111} planes. Dislocations, revealed by etch pits on a {111} face, occurred in rows that were traces of operative slip planes.

The Floating-Zone Melting of Boron and the Properties of Boron and Its Alloys

Pressed powder compacts of boron have been melted by the floating-zone technique. The compacts were initially bonded with boric acid, which was at least partially decomposed by heating to 300°C. Subsequently, heating to 600°C completely decomposed the boric acid to boron trioxide, which formed a liquid coating on the particles and after cooling strongly bonded the compact. One end of the compact was fitted into a graphite cup, which was used to heat the adjacent boron to a temperature suitable for inductive coupling within the floating-zone apparatus. A liquid zone was passed from the top to the bottom of the compact in an atmosphere of argon. The boron trioxide evaporated before the temperature reached the melting point of boron, approximately 2000°C.

Effects of compression and annealing on the structure and electrical properties of germanium

Germanium has been compressed under various conditions and has subsequently been annealed. These studies give direct evidence of the operation of the dislocation mechanism of plastic flow. No evidence of recrystallization has been found, but a domain structure composed of small angle boundaries is formed by large deformations at high temperatures. Annealable acceptor centers apparently due to point defects have been found and studied.