Disorder strengthening of ordered L1 2 alloys by face centered cubic (A1) precipitates

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.…”

“…5d,e; to make dislocations wavy is to make it longer, hence energy requirement for dislocation motion would be higher with the presence of HE-FCC particles. In this work, Hirsch's model 59,65 , was applied to evaluate the strengthening contribution in CRSS as:…”

“…5 d,e; to make dislocations wavy is to make it longer, hence energy requirement for dislocation motion would be higher with the presence of HE-FCC particles. In this work, Hirsch’s model 59 , 65 , was applied to evaluate the strengthening contribution in CRSS as: where is the CRSS, r is the average radius of FCC particles, f is the volume fraction of FCC particles in the L1 2 phase, b L12 is the Burgers vector in L1 2 phase, γ APB is the APB energy and K is the repulsive force between the edge superdislocations which can be stated as: And, G is the shear modulus, b fcc is the Burgers vector in FCC phase, ν is the Poisson’s ratio. To derive CRSS, the γ APB , b fcc , b L12 , ν and G were taken from the previous work 27 and JMatPro calculations 60 as 0.22 J/m 2 , 0.257 nm, 0.514 nm, 0.313 and 81 GPa, respectively.…”

A nickel based superalloy reinforced by both Ni3Al and Ni3V ordered-fcc precipitates

“…This enables the L1 2 Ni 3 Al population to be established and controlled prior to formation of D0 22 Ni 3 V, 40 Figure 1f. A two-step heat treatment was designed to investigate the potential to form hierarchical structures of D0 22 Ni 3 V within L1 2 Ni 3 Al precipitates, as is possible in B2 and L2 1 ordered-bcc precipitates [17] and L1 2 Ni 3 Al with A1 Ni precipitates [18,19,20].…”

“…In these alloys the Fe rich A2 matrix contains 60 − 200 nm B2 150 NiAl precipitates from within which 15 − 20 nm L2 1 precipitates nucleate and grow within the B2 precipitates [17]. This is similar to the precipitation of A1 Ni from within L1 2 Ni 3 Al [18,19,20] owing to the decreased solubility for Ni within Ni 3 Al with temperature. If the solubility for V within Ni 3 Al changed with temperature this would enable the precipitation of D0 22 Ni 3 V from within L1 2 Ni 3 Al.…”