Deformation Behavior of Sapphire Via the Prismatic Slip System

The deformation behavior of α ‐axis sapphire in tension from 1550° to 1850°C was studied in constant strain‐rate, differential strain‐rate, and differential‐temperature tests. The crystals deformed via the prismatic system, , resulting in stress‐strain curves with a significant yield drop, a region of work‐hardening which decreased in magnitude with increasing temperature, and a region of constant flow stress. The deformation was inhomogeneous with irregularly spaced slip bands containing a high density of glide dislocations and also basal dislocation debris. The flow behavior did not conform to simple diffusional or Peierls‐process models but could be rationalized on the basis of the creation of a super saturation of vacancies generated by the motion of jogs on gliding screw dislocations.