Grain-size-gradient nickel alloys I: Fabrication and tensile properties

As an alternative material for enhanced fatigue and/or creep properties, grain-size-gradient nickel alloys are fabricated through thermomechanical processing incorporated with systematic additions of grain growth inhibitors such as Al2O3 and MgO. By varying the grain size spatially within a sample geometry, an optimum combination of conflicting grain size effects is sought. The grain size in such oxide-treated regions shows a reasonable stability against high temperatures. The gradient structure is also found to influence tensile fracture mode and surface roughening, depending on the configuration of the gradient. The tensile behavior of these gradient alloys is examined and discussed in terms of the rule of mixtures. © 1988