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Key Factors Achieving Large Recovery Strains in Polycrystalline Fe–Mn–Si‐Based Shape Memory Alloys: A Review
Author(s) -
Peng Huabei,
Chen Jie,
Wang Yongning,
Wen Yuhua
Publication year - 2018
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201700741
Subject(s) - materials science , austenite , shape memory alloy , crystallite , microstructure , metallurgy , weldability , alloy
Fe–Mn–Si‐based shape memory alloys are the most favorable for large‐scale applications owing to low cost, good workability, good machinability, and good weldability. However, polycrystalline Fe–Mn–Si‐based shape memory alloys have low recovery strains of only 2–3% after solution treatment, although monocrystalline ones reach a large recovery strain of ≈9%. This review gives an overview of the improvement of recovery strains for polycrystalline Fe–Mn–Si‐based shape memory alloys. It is proposed that two fundamental aspects, that is, composition design and microstructure design, shall be satisfied for obtaining large recovery strains of above 6%. Alloying compositions determining the ceiling of recovery strains shall follow three guidelines: (i) Si content is 5–6 wt%; (ii) 20 wt% ≤ Mn ≤ 32 wt%; (iii) addition of elements strongly strengthening austenite matrix. Microstructure design includes coarsening austenitic grains and reducing twin boundaries as far as possible together with introducing a high density of stacking faults and second phases of strengthening austenite.