The formation mechanisms of surface nanocrystallites in β-type biomedical TiNbZrFe alloy by surface mechanical attrition treatment

摘要: Abstract A nanostructured surface layer was successfully performed on a biomedical β-type TiNbZrFe alloy by mechanical attrition treatment (SMAT). The results reveal that the along depth from treated to strain-free matrix could be divided into an outer nanocrystalline (0–30 μm), high-density dislocation region (30–200 μm) and inner with low-density dislocations twins (200–700 μm) when for 60 min. microhardness of is enhanced increases increasing time. Although {1 1 2} 〈1 1 1〉 twin coordinates deformations dislocations, this coordination only occurs in low strain area cannot affect formation. self-nanocrystallization mainly attributed movements. First, start move easily form bands certain crystal directions; then, multiple slips gradually tangles; after that, tangles increases, which divides primary grains many small domain areas. As high energies accumulate interfaces among these areas, lattice rotation can driven between adjacent finally resulting large number regions or angle grain boundaries.