Observations of the fine structure of superdislocations in Ni₃Al by field-ion microscopy

Strengthening Mechanisms in Polycrystalline Multimodal Nickel-Base Superalloys

“…In the model, cross-slip-induced hardening occurs in primary c¢ and secondary c¢ precipitates larger than 300 nm. An APB energy of 200 mJ/m 2 , an intermediate value among those reported in the literature, [52][53][54][55] was used in the majority of the analyses. As will be discussed later, this material property, while not well known, has a significant effect on strength.…”

Strength and Ductility of Intermetallic Compounds

“…6(b), consider shifting the top layer and all those above it by 1/2[T01], shown as b A in Fig. APB energies on (111) planes were measured by Taunt and Ralph [29] using field ion microscopy (FIM) and were found to be 250 to 350 mJm" 2 in Ni 3 Al while more recent measure ments by Veyssiere [30], Veyssiere et al [31] and Douin et al [32] were found to be 111 + 15 mJm" 2 . A single layer fault is created in which the stacking sequence is still locally fee (abcabc-stacking), but there are now B-B nearest neighbors where none exist in the unfaulted material.…”

“…(b) When the APB energy on (111) Direct observations of dislocations using FIM [29] and TEM [32,34] have revealed dislocations dissociated in Ni 3 Al according to scheme 3, but given the expected high energy of the CSF and the resulting close spacing of the Shockley partials, scheme 1 is possible even though it has not been observed. SISF's have been observed in Ni 3 Al [31,[38][39][40], Ni 3 Ga [41][42][43][44][45]; Cu 3 Au [33] and Zr 3 Al [46]; however, in general, the dislocation dissociation schemes observed were more complex than shown in Sec.…”

Order-Disorder Transitions in Substitutional Solid Solutions

“…in Fe-35aty0 A1 [55] and Fe-26atyo A1 [56], Ni,Ta [57], A1,Li [58], Ni,Ga [59], CuZn [go, 611, Fe-12.1 atyo Si [62], Ni,Fe [63], Ni,A1 [64], Cu,ZnNi [65], Cu,MnAl [66], NiAl [67]. However, such values must be considered carefully [68], in particular because the APB energy depends strongly on the state of order (it is approximately proportional to the square of the order parameter) : they should be compared with those obtained by other methods (field-ion microscopy [69], theoretical considerations). For the maximum order parameter, the APB energies lie between a few tens and several hundreds of mJ/m2 [66, 671, i.e.…”