Interplay between grain boundary segregation and electrical resistivity in dilute nanocrystalline Cu alloys

Abstract

The relationships between microstructure, controlled by alloying elements prone to grain boundary segregation, and electrical resistivity in sputtered nanocrystalline Cu were investigated. We find a non-monotonic dependence of the mean grain size on solute concentration for both Cu-Nb and Cu-Fe dilute alloys, with a concentration regime where the grain size increases over that of pure Cu before refining with further alloying. The electrical resistivity follows the same trend, suggesting a non-equilibrium processing route that remarkably gives rise to dilute nanocrystalline Cu alloys with lower resistivity, thermal stability, and enhanced mechanical properties relative to their pure nanocrystalline counterpart. Nanocrystalline (NC) metals have been the subject of intense research activity, driven largely by technological interests in their high hardness and strength. The results from decades of experiments and simulations point to the governing role of deformation physics unique to its coarse-grained counterparts, including grain boundary (GB) sliding, nucleation of dislocations from GBs and their subsequent isolated propagation, GB rotation, and stress-assisted grain growth [1,2]. Owing to the large volume fraction of material in near-GB regions in nanocrystalline metals, the properties of these materials are governed by interfacial phenomena.

Approaches to Measure the Resistivity of Grain Boundaries in Metals with High Sensitivity and Spatial Resolution: A Case Study Employing Cu

“…Moreover, theoretical and experimental studies show that segregation can either decrease or increase the GB resistivity depending on the GB type and alloying (impurity) element. 17 , 19 , 22 …”

“…Moreover, theoretical and experimental studies show that segregation can either decrease or increase the GB resistivity depending on the GB type and alloying (impurity) element. 17,19,22 The measurement of electrical resistivity of an individual GB in metals has been reported using several approaches. One possibility consists of measuring a macroscopic resistivity of a polycrystalline sample with a known number of GBs and then normalizing it by number of grains using mathematical models.…”

“…The atomic structure of a GB is determined by its crystallography, i.e., relative orientation between neighboring grains and the corresponding grain boundary plane, possible atomic translations at the GB, chemical composition, and temperature. ,, Computational studies on particular GB types confirm that their structure determines the resistivity values. − As a consequence, different types of coincidence site lattice (CSL) GBs can be distinguished by their values of resistivity. Moreover, theoretical and experimental studies show that segregation can either decrease or increase the GB resistivity depending on the GB type and alloying (impurity) element. ,, …”

Linear Complexions: Metastable Phase Formation and Coexistence at Dislocations

“…Over the last two decades, a variety of grain boundary complexions have been discovered and classified [2][3][4][5][6][7][8][9][10][11][12][13], with their substantial impact on a spectrum of physical properties of polycrystalline materials also being uncovered [14][15][16][17][18][19][20][21]. In contrast, linear complexions, defined as stable chemical and structural states confined at line defects or dislocations, have only been just recently found and represent a new prospective field of study in physics and materials science [22][23][24][25][26].…”

THE COMPARISON OF THE EXPERIMENTAL DATA AND THE EDUCATED ESTIMATES OF STRENGTH AND ELECTRICAL PROPERTIES OF Cu/Mg COMPOSITES WITH VARIOUS PROPORTIONS OF THE COMPONENTS

“…Очевидно, что прочностные свойства композитов с несмешивающимися компонентами в основном зависят от объемной доли более прочной фазы, а их проводящие свойства определяются медной матрицей. В то же время вклад как в прочностные свойства, так и в электросопротивление многоволоконных композитов вносят многочисленные поверхности раздела компонентов, поскольку они тормозят движение дислокаций и выступают как препятствия для носителей заряда [5]. Однако работ по рассмотрению влияния объемной доли интерфейса на физико-механические свойства композитов с медной матрицей явно недостаточно.…”