Stability of the High Temperature Beta Phase in Beryllium and Beryllium Alloys

As a result of the discovery of a body-centered cubic phase just below the melting point of pure beryllium, an investigation was carried out to determine the stability of this phase in different beryllium alloy systems. Binary alloys of beryllium with cerium, chromium, copper, iron, lanthanum, nickel, niobium, palladium, platinum, silicon, silver, vanadium and zirconium and the ternary system beryllium-nickel-palladium were investigated by differential thermal analyses. As a result of this investigation, the beryllium-rich portion of the beryllium-nickel phase diagram was established. Tentative phase diagrams of the beryllium-rich portions of the chromium-iron-silver-and silicon-beryllium alloys are also presented. Of all the elements investigated, nickel appears to have the greatest stabilizing effect on this body-centered cubic phase. The transformation temperature from beta to alpha was found to decrease in this system from 1265°C for pure beryllium to 1065°C for a Be - 8 a/o Ni alloy. The latter alloy was used for investigation of the crystal structure of the high temperature phase. This was found, in agreement with the work of Martin and Moore on unalloyed beryllium, to have a body-centered cubic lattice, the alloy having a lattice parameter ao = 2.60 Å. A limited amount of work was done in attempting to retain the beta phase in a Be - a/o Ni alloy by quenching. The experiments performed thus far indicate the possibility of retention to room temperature. Hot working experiments were also performed on this alloy.