Zhou X, Mianroodi J R, Kwiatkowski da Silva A, Koenig T, Thompson G B, Shanthraj P, Ponge D, Gault B, Svendsen B, Raabe D
Max-Planck-Institut für Eisenforschung, 40237 Düsseldorf, Germany.
Material Mechanics, RWTH Aachen University, 52062 Aachen, Germany.
Sci Adv. 2021 Apr 16;7(16). doi: 10.1126/sciadv.abf0563. Print 2021 Apr.
Dislocations are one-dimensional defects in crystals, enabling their deformation, mechanical response, and transport properties. Less well known is their influence on material chemistry. The severe lattice distortion at these defects drives solute segregation to them, resulting in strong, localized spatial variations in chemistry that determine microstructure and material behavior. Recent advances in atomic-scale characterization methods have made it possible to quantitatively resolve defect types and segregation chemistry. As shown here for a Pt-Au model alloy, we observe a wide range of defect-specific solute (Au) decoration patterns of much greater variety and complexity than expected from the Cottrell cloud picture. The solute decoration of the dislocations can be up to half an order of magnitude higher than expected from classical theory, and the differences are determined by their structure, mutual alignment, and distortion field. This opens up pathways to use dislocations for the compositional and structural nanoscale design of advanced materials.
位错是晶体中的一维缺陷，使其具有变形、力学响应和输运特性。它们对材料化学的影响则鲜为人知。这些缺陷处严重的晶格畸变促使溶质向其偏析，导致化学性质在空间上出现强烈的局部变化，从而决定了微观结构和材料行为。原子尺度表征方法的最新进展使得定量解析缺陷类型和偏析化学成为可能。如此处针对铂 - 金模型合金所示，我们观察到一系列特定于缺陷的溶质（金）修饰模式，其种类和复杂性远超科特雷尔气团模型的预期。位错的溶质修饰量可比经典理论预期高出多达半个数量级，且这些差异由位错的结构、相互排列以及畸变场决定。这为利用位错进行先进材料的成分和结构纳米尺度设计开辟了道路。
