Unraveling irradiation induced grain growth with in situ transmission electron microscopy and coordinated modeling

Abstract

Nanostructuring has been proposed as a method to enhance radiation tolerance, but many metallic systems are rejected due to significant concerns regarding long term grain boundary and interface stability. This work utilized recent advancements in transmission electron microscopy (TEM) to quantitatively characterize the grain size, texture, and individual grain boundary character in a nanocrystalline gold model system before and after in situ TEM ion irradiation with 10 MeV Si. The initial experimental measurements were fed into a mesoscale phase field model, which incorporates the role of irradiation-induced thermal events on boundary properties, to directly compare the observed and simulated grain growth with varied parameters. The observed microstructure evolution deviated subtly from previously reported normal grain growth in which some boundaries remained essentially static. In broader terms, the combined experimental and modeling techniques presented herein provide future avenues to enhance quantification and prediction of the thermal, mechanical, or radiation stability of grain boundaries in nanostructured crystalline systems.

Thermal stability and irradiation response of nanocrystalline CoCrCuFeNi high-entropy alloy

“…Due to the strong texture of the films, only the (111) peak exhibits a reasonable intensity, as shown in Fig. 9 Temperature-dependent grain growth, either thermally-induced or defect-stimulated, has been reported [41,[70][71][72][73][74][75][76][77][78]. Simulations reveal three grain-growth mechanisms, driven by grain rotation, curvature, and disorder [79][80][81][82], respectively.…”

Irradiation‐Induced Extremes Create Hierarchical Face‐/Body‐Centered‐Cubic Phases in Nanostructured High Entropy Alloys

“…The decreasing density of the GBs is attributed to irradiation-induced grain growth. [32,33] From the 1D concentration profile across the GB, significant elemental redistribution is observed that indicates a peak distribution of Cr at the GB. The wavy distribution of Cr inside the columnar grains is also pronounced (Figure 4b5), the combination of the microstructural analysis inside the crystalline grains suggests that it may be induced by the compositional differences between the adjacent FCC and BCC phases.…”

Atomic-scale investigation of triple junction role on defects binding energetics and structural stability in α-Fe

“…Recent development of advanced materials such as nanoporous [6,7], nanocrystalline (NC) [8][9][10][11][12], and nanocomposite materials [13,14] show promise for use as structural materials in extreme environments [9,10]. However, the grand challenge with broader applicability of such nanostructured materials has been the stability of the non-equilibrium microstructure during processing and deformation [15][16][17][18][19]. This significant degradation in properties of nanostructured materials is in part due to an increase in the large volume fraction of GBs along with TJs, which lack long-range crystalline order leading to diffusional processes such as sliding and/or rotation [20].…”

“…Further, in nanostructured materials, such as NC metals, as the mean grain size decreases below 10 nm, the percent microstructure constituted by GBs and TJs increases and can be in excess of 50% [21,22]. Thus, due to the large volume fractions of non-equilibrium defects, NC metals exhibit altered physical responses to deformation, temperature, and radiation [15][16][17][18][19], i.e., the structural stability of NC materials is driven by GBs (planar defects), TJs (line defects), and their underlying structures [23,21]. Hence, a fundamental understanding of the relationship between the line/planar defect structures and the associated properties is highly relevant to develop stable, interface-dominant materials.…”