Strengthening of an L1(2)-ordered gamma '-intermetallic by disordered gamma-particles. Part I: Computer simulations

Strengthening of an L1(2)-long-range ordered gamma ' -intermetallic by cohe rent disordered spherical gamma -particles has been investigated by compute r simulations and by measuring the critical resolved shear stress (CRSS) of Ni69Co9Al18Ti4. In the present Part I the simulations and their results ar e communicated in Part II experimental data taken for Ni69Co9Al18Ti4 will b e reported. The simulations yielded numerical values for the CRSS tau (p). The average radii r and the volume fractions f of the gamma -particles have been varied widely: 1 nm less than or equal tor less than or equal to 19 n m and 0.04 less than or equal tof less than or equal to0.10. The numerical results tau (p) (r greater than or equal to7 nm,f) can be well represented by Friedel's relation - provided the dissociation of the dislocations into partial dislocations is allowed for in the calculation of the dislocation l ine tension. (C) 2001 Acta Materialia inc. Published by Elsevier Science Lt d. All rights reserved.