Hot isopressing beryllium - the effect of temperature and pressure

The effect of lowering the compaction temperature and increasing the pressure on the mechanical properties of fully dense beryllium is reported. Although material is pressed at high pressure to nominal full density, at temperatures below 9000C the product has inferior tensile ductility; consequently no benefit was gained as a result of operating conditions outside the capability of the currently installed production equipments. The isopressed powder data are compared with the results of an extensive programme on uniaxial pressed hot pressed beryllium powder of high and normal commercial purity. The 'phenomenon' of hot isopressed material 'swelling' during vacuum heat treatment (approximately 11500C) is attributed to the formation of hydrogen from the decomposition of a solid impurity. Swelling can be controlled to < 1% by outgassing prior to hot isopressing. (author)