Composition formulas of Cu-Ni industrial alloy specifications

Abstract

It was recently known that the compositions of industrial alloy specifications generally satisfy simple composition formulas issued from short-range-order structural units in their basic solid solutions. In present work, Cu-Ni face-centered-cubic alloys were further addressed by introducing the cluster-plusglue-atom model for the short-range-order structural descriptions. Composition formulas covering only the first twelve and the second six neighbor shells in the face-centered-cubic lattice are proposed, [Cu-Cu12](Cu,Ni)6 for the Cu-rich alloys and [Ni-Ni12]Cu6 ~ [Ni-Ni12](Cu5Ni) for Monel alloy, the only Ni-rich alloy specficiation, where the square-bracketed part represents a cuboctahedral cluster. The alloy specification selection is also discussed in terms of valence electron numbers per unit formula. The present work confirms that well-established industrial alloys have simple composition rules that reflect the intrinsic short-range-order local structures in the solid solutions.

Impact of Short-Range Clustering on the Multistage Work-Hardening Behavior in Cu–Ni Alloys

“…However, such explanations are inapplicable to the present Cu-Ni alloys with high SFEs, since cross slip is prevalent, which aggravates dislocation annihilations during deformation [26,27]. In fact, in addition to altering the SFE, the addition of alloying elements brings about a positive effect on the increase of SRO/SRC in alloys [23,28,29]. Considering that the SRC/SRO could suppress the cross slip [21], it is believed that the increasing degree of SRC due to the addition of Ni element should be a reason for the enhancement of dislocation density in the present Cu-Ni alloys, leading to a stronger work-hardening capacity.…”

“…As is well known, for metallic alloys, solute atoms do not disperse perfectly at random in alloying matrix, and the solute and solvent atoms in solid solutions are generally apt to form short-range order structures at atomic level. As solute atoms tend to neighbor with solvent atoms, SRO is formed, while SRC tends to form in the case that the solute atoms favor their own segregation [23]. Gerold and Karnthaler [21] believed that the existence of SRO or SRC structures was the crucial factor evoking planar slip in FCC alloys, and other parameters, such as the SFE and yield strength, were only supporting ones.…”

Spherical periodicity as structural homology of crystalline and amorphous states

“…This is actually the clusterplus-glue-atom model that has been used by us to interpret precisely many good BMGs and even some industrial alloys [25,26]. In the structural unit, the first nearestneighbor cluster is located within the r 1 zone with the strongest negative potential, and the glue atoms preferentially fall within the r 1.5 zone with the strongest positive potential.…”

Strategies for Achieving Strength–Ductility Synergy in Face‐Centered Cubic High‐ and Medium‐Entropy Alloys

“…[ 231 ] In fact, for traditional solid‐solution alloys, solute atoms are not completely dispersed in a random way in alloying matrix, and the solute and solvent atoms usually tend to form short‐range order structure at atomic level due to the interactions between them. [ 232 ] The origin of SRO formation in alloys could be attributed to multiple sources such as enthalpy‐driven bonding, [ 233 ] magnetic interactions, [ 234 ] electronic interaction, [ 235 ] etc. In terms of the effect of SRO on the deformation mechanism, the earliest study can be traced back to the work of Clément [ 236 ] in 1984.…”