High-strength bulk nano-crystalline silver prepared by selective leaching combined with spark plasma sintering

In this work, we propose a novel technique to prepare bulk nano-crystalline metals or alloys using selective chemical leaching and spark plasma sintering. The bulk nano-crystalline silver was successfully prepared by this technique. The average grain size of the bulk material was 50 nm. The Vickers hardness, compressive yield strength, ultimate compressive strength and maximum compressive strain of the nano-crystalline silver were 155 HV 0.04, 520 MPa, 620 MPa and 20%, respectively. Micro-crystalline and coarse-grained silver were also prepared as reference materials. The bulk nano-crystalline silver prepared by the novel technique exhibited the highest hardness and compressive strength reported to date. The mechanical properties of the material from this work are compared to those from other works using the Hall-Petch relationship, and the relevant properties are discussed in relation to the preparation technique and structural characteristics of the materials. (C) 2015 Elsevier B.V. All rights reserved.