An effective approach to produce a nanocrystalline Ni–Ti shape memory alloy without severe plastic deformation

• Bulk nanocrystalline Ni–Ti alloy was produced without imposing a severe plastic deformation.
• The novel process was effective in promoting recrystallization and limiting grain growth.
• Bulk nanocrystalline Ni–Ti alloy showed noticeably enhanced shape memory properties.

Bulk nanocrystalline (d = 20–40 nm) Ni–Ti shape memory alloy was produced via cold marforming, followed by optimum post-heat treatment. The total accumulative strain (ε ∼ 0.7) during the process was much lower than that typically imposed during severe plastic deformation operations (i.e., 5 ≤ ε ≤ 12). In-situ heating transmission electron microscopy revealed that the present process was effective in promoting static recrystallization and limiting grain growth. The nanocrystalline alloy exhibited enhanced shape memory behaviors.

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