“…Prior attempts to refine the grain structure in Zr via SPD either led to submicron grains with grain diameters >100 nm [23,24,39,40] or a fraction of nanograins of Zr with an alternate crystal structure (omegaZr, beta-Zr or fcc Zr) [23][24][25]41]. With single-phase commercial purity Zr, the final grain size reached with the ARB technique was 400 nm [42]. Bimetallic composites with hcp constituents such as Mg-Al [18], Ti-Al [20], CuZn [16], Cu-Zr [17], Zr-Nb [40], and Al-Zn [15] have been synthesized using ARB.…”