ANISOTROPY OF THE CRITICAL RESOLVED SHEAR-STRESS OF A SUPERALLOY CONTAINING 6 VOL-PERCENT L1(2)-ORDERED GAMMA'-PRECIPITATES

Single crystals of the gamma'-strengthened nickel-base superalloy NIMO NIC PE16 have been compression tested in the temperature range 683-114 3 K. Four different orientations of the specimens have been studied: [ 0 0 1],[($) over bar 123],[011] and [($) over bar 111]. They were eith er in the homogenized, single-phase state or in the peak-aged state. T he critical resolved shear stress (CRSS) of the homogenized specimens was isotropic at 683 K. The CRSS of the peak-aged specimens, containin g 6 vol.% of L1(2)-long-range ordered gamma'-precipitates of 25 nm rad ius, was anisotropic at 683 K and at 989 K: the [001]-orientated speci mens were the softest ones, the CRSS increased as the orientation move d towards [011] or [($) over bar 111]. This is the same orientation de pendence found for the CRSS of single-phase L1(2)-ordered materials. T he interpretation of the anisotropy of the CRSS of NIMONIC PE16 follow s that given for single-phase L1(2)-long-range ordered materials.