Effect of hydrogen and grain boundaries on dislocation nucleation and multiplication examined with a NI-AFM

A nanoindenting AFM (NI-AFM) with an environment chamber was constructed to study the effect of hydrogen on decohesion and dislocation nucleation and the effect of grain boundaries on dislocation nucleation and multiplication. Ultra fine grained Ni single crystals were examined. It could be clearly shown that hydrogen influences the pop in width and length. Testing single grains with grain sizes below one micron at different rates inside a NI-AFM showed that the rate dependence of ultra fine grained Ni is a result of the interaction of the growing dislocation loops with the boundary.