Abrasive wear response of nanocrystalline Ni–W alloys across the Hall–Petchbreakdown

Strain localization in a nanocrystalline metal: Atomic mechanisms and the effect of testing conditions

“…Away from the strain localization, grains remain equiaxed and a similar size as the starting structure. Mechanically-induced grain growth has been observed in a number of nanocrystalline metals such as Al, 10,41 Ni, 42,43 and Cu, 9 as well as alloys such as Ni-Fe, 44,45 Ni-W, 46,47 and Co-P. 48 This grain growth can be caused by a combination of grain boundary migration and coalescence due to grain rotation, and has been shown to be driven by high shear stress. 49 While small areas of high shear strain are observed at ε = 5.0%, a path of high strain that spans the sample becomes clear at approximately ε = 5.4%, after a major stress drop in the stress-strain curve presents in Fig.…”

Combined effects of nonmetallic impurities and planned metallic dopants on grain boundary energy and strength

“…Grain boundaries play an important role in governing the mechanical, functional, and kinetic properties of a great many engineering materials, but these features are especially important for nanostructured materials [1][2][3][4]. Nanostructured materials exhibit many advantages compared to microcrystalline materials, including superior strength [5,6] as well as increased resistance to wear [7] and fatigue [8]. However, one of the limitations of nanostructured materials is their lack of thermal stability, which is attributed to the high grain boundary fraction providing a large driving force for grain growth [9][10][11].…”

Amorphous complexions enable a new region of high temperature stability in nanocrystalline Ni-W

“…Nanocrystalline metals, commonly defined as having an average grain size less than 100 nm, have demonstrated a variety of beneficial characteristics including increased strength [1,2], wear resistance [3][4][5], and fatigue lifetime [6]. These enhanced properties are largely attributed to the high volume of grain boundaries present in these materials [7] and make nanocrystalline metals promising candidates for use in extreme environments, but the same grain boundaries that generate these desirable characteristics in turn serve to frustrate their application.…”