Abstract
Hardness measurements and microscopic observations by both optical and transmission electron microscopy were carried out mainly on a beryllium-3wt% iron alloy.
The alloy was solution-treated at 1150°C, followed by oil-quenching, and aged at 400° to 700°C for a various time. In the quenched specimens, helices and loops of dislocations were observed. The ageing treatment resulted in climbing of the dislocations and also preferential precipitation on dislocations as well as at grain-, twin-, and sub-boundaries.
Although the change in hardness due to ageing was not so large, two different stages were found in the ageing process, and it was considered that the first stage was associated with the climbing of dislocations and preferential precipitation onto dislocations, and the second stage with effective homogeneous precipitation.
The composition of precipitates was identified to be Be11Fe, and the crystal structure of the precipitates and their orientation relationship with the matrix were the same as those reported by Rooksby.
