A grain-size-dependent structure evolution in gradient-structured (GS) Ni under tension

• 来源期刊: 纳米材料科学（英文版）
• 年，卷（期）: 2020,（1）
• 页码范围: 39-49
• 页数: 11页
• 语种: 中文

摘要

This work outlines an experimental investigation of grain-size-dependent structure evolution under tension in nickel with a grain size gradient.Two opposite and competing processes,grain refinement and coarsening,were examined within one specimen,due to the widely ranging grain size in gradient-structured (GS) Ni.A tension-induced minimum grain size of approximately 280 nm was determined in GS Ni,which is comparable to those obtained by severe plastic deformation processes.The minimum grain size was phenomenologically explained using a dislocation model.Below the minimum grain size,the Ni's grain coarsening ability peaked at approximately 50 nm and progressively decreased with decreasing grain size,showing an inverse grain-size-dependent coarsening tendency.Moreover,this inverse grain coarsening behavior was related to a transition in the deformation mechanism,through which the deformation process was accommodated more by partial dislocation than by full dislocation below a critical grain size.This was confirmed by observation of the microstructure and low temperature tensile testing results.This work demonstrates a high-throughput strategy for exploring the minimum grain size and grain-size-dependent coarsening in metals.