Microstructural progression of shear-induced mixing in a CuNi alloy

Shear deformation has been highlighted in multiple research efforts for its ability to impart novel microstructures that demonstrate improvements in mechanical properties. When used to process and densify powdered material, these shear-based consolidation techniques are commonly referred to as friction consolidation (FC). In this paper, the microstructural evolution from compacted Cu and Ni powders to a consolidated Cu0.5Ni0.5 alloy is examined. Various stages of porosity reduction and deformation are shown. Deformation was observed to accumulate preferentially in the more ductile material early in the process, leading to the formation of a tortuous microstructural zone. Porosity reduction was extensive, decreasing from similar to 65% in the pre-compacted state to similar to 1% in the fully consolidated alloy. The final consolidated alloy showed a similar to 2x hardness improvement over the unalloyed, compacted material. Unique aspects of this work include demonstration of FC processing to produce an equiaxed, sub-micrometer grain size in samples within a 0.5 to 2 min processing time. The results point to future opportunities to implement shear deformation during powder densification to expand the range of property outcomes in bulk materials.

Automated summary

The study examined the microstructural evolution from compacted Cu and Ni powders to a consolidated Cu0.5Ni0.5 alloy, showing stages of deformation and porosity reduction leading to significant hardness improvement in the final alloy. This work demonstrates the potential of shear deformation during powder densification to broaden property outcomes in bulk materials.