Putting fatigue to rest via solute-pinned boundaries

All metals have their limit when it comes to enduring fatigue damage. The best commercial alloys can survive 10 7 cycles at cyclic stress amplitudes up to approximately 850 MPa. Here we explore the possibility of exceeding that limit by preventing dislocation-mediated crack nucleation processes. In the current study, a model solute-stabilized nanocrystalline alloy (Pt-10 atom% Au) is shown to sustain no fatigue damage even after 10 10 cycles at stress amplitudes above 1 GPa (corresponding to an applied maximum strain of 0.65% under fully reversed loading). To understand the origins of that remarkable fatigue resistance, atomistic simulations and electron microscopy point to the role of solute-stabilized grain boundaries which prevent the nanostructured alloy from undergoing fatigue-induced grain growth and subsequent dislocation-mediated fatigue damage. Such findings point to new pathways to suppress crack initiation in nanostructured metals, offering a possibility of future metals that are impervious to fatigue failure.