On the exceptional damage-tolerance of gradient metallic materials

By R. Cao, Qin Yu, J. Pan, Yan Lin, Andrew Sweet, Yi Li, R. Ritchie. Materials Today, 2020

162 citations recorded by the source corpus.

Abstract An experimental study is described on the fracture toughness and micro-mechanisms associated with the initiation and propagation of cracks in metallic nickel containing marked gradients in grain size, ranging from ∼30 nm to ∼4 μm. Specifically, cracks are grown in a gradient structured (GS) nickel with grain-size gradient ranging from the coarse macro-scale to nano-scale (CG → NG) and vice versa (NG → CG), with the measured crack-resistance R-curves compared to the corresponding behavior in uniform nano-grained (NG) and coarse-grained (CG) materials. It is found that the gradient structures display a much-improved combination of high strength and toughness compared to uniform grain-sized materials. However, based on J-integral measurements in the gradient materials, the crack-initiation toughness is far higher for cracks grown in the direction of the coarse-to-nano grained gradient than vice versa, a result which we ascribe primarily to excessive crack-tip blunting in the coarse-grained microstructure. Both gradient structures, however, display marked rising R-curve behavior with exceptional crack-growth toughnesses exceeding 200 MPa.m½.

Subfields: Materials Chemistry, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/5ed7dd779101dbf8442f679431f7df83a25becc4

How researchers see this paper

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In Materials Chemistry

1. R. Ritchie
2. Qin Yu

In Mechanical Engineering

1. R. Ritchie

Citations in the corpus

• On the impact toughness of gradient-structured metals (2020, background): “Coarse-grain structures in nickel are known to induce marked crack-tip blunting which can generate high toughness [23]; however, once they are transformed into dynamically recrystallized ultra-fi ne grains, the resistance to crack propagation becomes far lower.”