Micro-mechanical measurements of fracture toughness of bismuth embrittled copper grain boundaries

Abstract

Measuring the fracture properties of single grain boundaries has until now required macroscopic bi-crystals which are expensive and not always available. We describe a method for fracture testing using micro-cantilevers, manufactured using focussed ion beam machining and tested using a nanoindenter. We have used the method to measure the fracture toughness of selected grain boundaries in bismuth-embrittled copper. This technique is applicable to grain boundaries in other brittle polycrystalline samples for which large bi-crystals cannot be produced for conventional testing.

Keywords:

• fracture toughness
• grain boundaries
• embrittlement
• focussed ion beam
• nanoindentation