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日本钢管公司新研制成功一种形状回复率高达5％以上的铁基形状记忆合金。该合金含Cr 5～20％,Si 2～8％,另加Mn(0.1～14.8％),Ni(0.1～20％)、Co(0.1～30％)、Cu(0.1～3％)、N(0.001～0.4％)之中的至少一种元素,并满足公式Ni+0.5Mn+0.4Co+0.06Cu+0.002N≥0.67(Cr+1.2Si)-3,以确保形成奥氏体组织。考虑优良的形状记忆特性须满足下列条件:1)在规定温度下对合金进行塑性加工前,合金必须主要由γ母相组成,而且,在该温度下加工时,发生由母相转变为ε马氏体;2)γ相的堆垛层错能低,在塑性加工时,由γ母相转变为ε马氏体,而不转变为α′马氏体;3)γ屈服强度必须相当高,在塑性变形时,在合金结晶结构中不发生滑移变形。
Japanese tube company newly developed a shape recovery rate of up to 5% or more of iron-based shape memory alloy. The alloy comprises 5-20% of Cr, 2-28% of Si, plus Mn of 0.1-1.8%, Ni of 0.1-20%, Co of 0.1-30%, Cu of 0.1-3%, N (0.001-0.4%) and satisfies the formula of Ni + 0.5Mn + 0.4Co + 0.06Cu + 0.002N ≧ 0.67 (Cr + 1.2Si) -3 to ensure the formation of an austenitic structure. Considering the excellent shape memory characteristics, the following conditions must be satisfied: 1) The alloy must mainly consist of the γ parent phase prior to the plastic working of the alloy at the specified temperature, and the transformation from the parent phase to the ε horse takes place at this temperature 2) the stacking fault of the γ phase is low, and during the plastic working, the γ parent phase is transformed into the ε martensite without changing to α ’martensite. 3) The γ yield strength must be quite high, In the plastic deformation, the alloy crystal structure does not occur in the slip deformation.