Search

The origin of “extra” spots in electron diffraction patterns taken from retained austenite and martensite in Fe-7 pct Al-2 pct C has been investigated. The present interpretation differs from that of previous investigators. It is concluded that a high density of fine carbide precipitates 50A in diameter is responsible for the extra reflections. The precipitates have the perovskite structure and grow epitaxially in the austenite during quenching. When martensite forms at a lower temperature, the precipitates are transformedin situ.

In order to study the recovery process of gold thin films deposited on an amorphous carbon film kept at 80 K, the electron diffraction method and transmission electron microscopy were used. It was found from the measurement of the intensity, the radius and the half width of the diffraction rings that the films had three distinct recovery stages between 80 and 360 K; that is, from 100 to 180 K, 200 to 280 K and 300 to 360 K. In the temperature range between 200 and 300 K grain boundaries began to migrate and above 300 K the grains with the 111 planes parallel to the film surface grew preferentially.

The angular correlation of gamma rays from the annihilation of positrons in liquid mercury alloys is measured. The momentum distribution of conduction electrons in liquid mercury alloys, especially in liquid Hg - 4 at. %Na, shows an anomalous k -dependence near the Fermi momentum.