Physical Properties

Beryllium has a close-packed hexagonal crystal structure with a = 0.2286 nm and c = 0.3584 nm and a c/a ratio of 1 to 1.56. This value is low compared to other metals such as titanium (1 to 1.58). Partly as a result of this c/a ratio, slip occurs almost exclusively on basal planes, with a Burger's vector of b = 3<ll20>. Slip also can occur--with much greater difficulty, however—on first-order prism planes (b = 3<ll5o>), and with even more difficulty on second-order pyramidal planes ({1122} with b = 3<ll23>) (Ref 4).

Basal slip is the predominant deformation mode, however. Basal cleavage is the predominant fracture mode. These crystal structure characteristics affect the shape of powder particles and subsequently affect billet properties.

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