TEM observation and computer simulation of the interaction of superlattice dislocations with disordered γ-precipitates in L12-ordered γ′-(Ni,Co)3(Al,Ti) intermetallics

Creep strengthening of Ni3(Al, Si) intermetallic alloy by ductile precipitates

“…This pinning mechanism causes hardening of the alloy, in constant strain rate tests [5] as well as in the present creep tests. This is in agreement with the experimental work on a (Ni, Co) 3 (Al, Ti) alloy and the computer simulations of Nembach and his students [17,[32][33][34] who considered the interaction of superdislocations in the g 0 matrix with spherical g precipitates. The maximum resolved shear stress needed by the superdislocations to pass through the g precipitates is about 40-50% of the critical resolved shear stress [17,34].…”

“…This is in agreement with the experimental work on a (Ni, Co) 3 (Al, Ti) alloy and the computer simulations of Nembach and his students [17,[32][33][34] who considered the interaction of superdislocations in the g 0 matrix with spherical g precipitates. The maximum resolved shear stress needed by the superdislocations to pass through the g precipitates is about 40-50% of the critical resolved shear stress [17,34]. This value is to be compared with the contribution of the threshold stress s 0 , measured above and caused by precipitates and by the dislocation substructure of the matrix, to the applied stress s: s 0 /s varies experimentally from 50 to 79%.…”

“…5a and b, the dislocations in the same area are imaged in two different weak-beam conditions. The dislocations are very long and straight, of screw nature as observed by Liu et al [17] by compression tests at room temperature. In the thinner part of the sample, the (super)dislocations are clearly dissociated in two (super)partials.…”

Hierarchical microstructure strengthening in a single crystal high entropy superalloy

“…Previous studies from Nemoto et al 55 , Hirsch et al 59 , Pretorius et al 61,62 , Liu et al 63,64 and Ardell et al 65 have deduced the strengthening contribution for ordered matrix by disordered particles; dislocations inside the L1 2 phase could be attracted to the disordered FCC particles that had no APB penalty and possessed shorter magnitude of burgers vector. This can explain the wavy superdislocations observed by TEM in Fig.…”