Atomistic modeling of interfacial segregation and structural transitions in ternary alloys

Abstract

Grain boundary engineering via dopant segregation can dramatically change the properties of a material. For metallic systems, most current studies concerning interfacial segregation and subsequent transitions of grain boundary structure are limited to binary alloys, yet many important alloy systems contain more than one type of dopant. In this work, hybrid Monte Carlo/molecular dynamics simulations are performed to investigate the behavior of dopants at interfaces in two model ternary alloy systems: Cu-Zr-Ag and Al-Zr-Cu. Trends in boundary segregation are studied, as well as the propensity for the grain boundary structure to become disordered at high temperature and doping concentration. For Al-Zr-Cu, we find that the two solutes prefer to occupy different sites at the grain boundary, leading to a synergistic doping effect. Alternatively, for Cu-Zr-Ag, there is site competition because the preferred segregation sites are the same. Finally, we find that thicker amorphous intergranular films can be formed in ternary systems by controlling the concentration ratio of different solute elements.

Ag Surface and Bulk Segregations in Sputtered ZrCuAlNi Metallic Glass Thin Films

“…Therefore, we suggest the formation of a new Ag-and Zr-rich MG whose elemental distribution is inhomogeneous. Ag has been known to change the local structure of Cu-containing metallic glasses because of the positive heat of mixing of Ag and Cu [33,34]. However, these changes seem to also depend on the Ag concentration.…”

“…The detection of metallic Ag at high substrate temperature and high Ag contents indicates limited metastable solubility of Ag in the MG, and the simultaneous growth of Ag and MG. The limited solubility of Ag in the MG could be assigned to the positive heat of mixing of Ag and Cu [ 33 , 34 ]. Aside from that binary, Ag-Ni [ 35 ] also exhibits a positive heat of mixing while those of the remaining binaries (i.e., Ag-Zr [ 33 ] and Ag-Al [ 36 ]) are negative.…”

“…Ag has been known to change the local structure of Cu-containing metallic glasses because of the positive heat of mixing of Ag and Cu [ 33 , 34 ]. However, these changes seem to also depend on the Ag concentration.…”

Discovery of a Wide Variety of Linear Complexions in Face Centered Cubic Alloys

“…While the Ni-Fe potential has already been used to investigate linear complexion formation in body centered cubic alloys [26] (i.e., in the Fe-rich side of the phase diagram), the potentials for the Cu-Zr, Al-Zr, and Al-Cu systems have all been used to capture planar complexion transitions at grain boundaries in face centered cubic alloys in prior studies [16,41,42]. Equilibrium states were obtained with hybrid Monte Carlo/molecular dynamics simulations using a parallel algorithm proposed by Sadigh et al [43].…”

Grain boundary segregation transitions and critical phenomena in binary regular solutions: A systematics of complexion diagrams with universal characters

“…Various GB complexions and segregation-induced GB transitions have also been observed in simpler metallic alloys [24][25][26][27][28][29][30][31][32][33]. In addition to the lattice [10,34] and phase-field [11,12] models, the occurrences of first-order GB transitions have been suggested by atomistic simulations [35][36][37][38][39] and experimentally evident in Si-Au [40]. Recently, GB structural transition in elemental Cu [41] and GB topological phase transitions [42] have also been revealed.…”