Superelastic-superplastic powder-metallurgy NiTi shape memory alloy made by meso-scale particles

细观颗粒超弹超塑性粉末冶金镍钛形状记忆合金

• 批准号: 07555478
• 负责人: HASHIMOTO Satoshi
• 金额: $ 0.19万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07555478/
• 关键词: powder metallurgy; NiTi; superelasticity; shape mewary alloy; superplasticity; martenrite; Powder metallurgy; NiTi; super elasticity; shape memory alloy; super plasticity; martensite; fatigue; power metallurgy; Ni Ti; superelasticity; shap

This is the first report for the powder metallurgy of titanium-nickel shape memory alloy having both shape memory and mechanical strength comparable to the alloy made by casting and wire-drawing. The fatigue properties and mechanism of the fracture were also investigated.The process for the powder metallurgy is as follows ; Titanium-Nickel alloy powder was produced by Plasma Rotation Electrode Process. The method was used to suppress the impurity contamination during atomizing process. The powder with an average diameter of 0.287mm was hot-pressed by Hot Isosotatic Pressing, and a compact having a relative density of 99.7% was obtained. The martensitic transformation temperature was identical to that of the ingot used for making the powder.Monotonic tensile test of the compact showed the shape memory strain and also the superelastic strain of 7% : the stress-strain behavior was almost identical to the cast alloy. However, it fractured by the deformation above 7%, which is much smaller than in cast alloys.In the case of cyclic tensile deformation, the initiation and propergation of crack of the compact happenned by smaller tensile strain. The fracture occurred by the cleavage of the powder surfaces. By in-situ observation of the surface relief of tensile specimens, it is found that the stress-induced martensitic transformation develops by an inhomogenerous manner, which resembles the propagation of Ruders Band. The crack nucleated within the bands. Therefore, the fatigue life of the compact did not depend explicitely on the amplitude of tensile deformation.

本文首次报道了用粉末冶金法制备钛镍形状记忆合金，该合金具有与铸造和拉丝相媲美的形状记忆和机械强度。采用等离子旋转电极法制备了钛镍合金粉末，并对其疲劳性能和断裂机理进行了研究。该方法用于抑制雾化过程中的杂质污染。将平均直径为0.287mm的粉末通过热等静压进行热压，并且获得相对密度为99.7%的压块。马氏体相变温度与用于制造粉末的锭的马氏体相变温度相同。压坯的单调拉伸试验显示形状记忆应变和7%的超弹性应变：应力-应变行为与铸造合金几乎相同。在循环拉伸变形条件下，压坯裂纹的萌生和扩展是在较小的拉伸应变下发生的。断裂是通过粉末表面的解理发生的。通过对拉伸试样表面浮凸的原位观察，发现应力诱发马氏体相变以不均匀的方式发展，类似于Ruders带的扩展。裂纹在带内成核。因此，压坯的疲劳寿命并不明显依赖于拉伸变形的幅度。

项目成果

S.Onaka: "Retardation of Intergranular Fracture at Intermediate Temperatures by a Boundary node in a Cu-9at.%Pl Alloy Tricrystals" Acta Metall Maters. 43. 307-311 (1995)

S.Onaka:%20"延迟%20of%20粒间%20断裂%20at%20Intermediate%20温度%20by%20a%20边界%20node%20in%20a%20Cu-9at.%Pl%20合金%20Tricrystals"%20Acta%20Metall%20Maters

S.Hashimoto: "Fatigue Crack Initiation and Propagation in Compact Tension Copper Single Crystals" Zeitschrift fur Metallkde.87. 128-134 (1996)

S.Hashimoto：“致密张力铜单晶中的疲劳裂纹萌生和扩展”Zeitschrift Fur Metallkde.87。

S.Onaka: "Retardation of Intergranular Fracture at Intermediate Temperature by a Boundary node in a Cu-9at.70Hl Alloy Tricrystal" Acta Metall.Mater.43. 307-311 (1995)

S.Onaka：“Cu-9at.70Hl 合金三晶中的边界节点在中温下延缓晶间断裂”Acta Metall.Mater.43。

S.Onaka: "Determination of the Aspect Ratio of a spheroidal Perticle by Steres Observation" Materials Characterization. 34. 167-172 (1995)

S.Onaka：“通过立体观察确定球形颗粒的纵横比”材料表征。

S.Onaka: "Determination of the Aspect Ratio of a spheroidal Particla by Stereo observation" Materials Characterization. 34. 167-172 (1995)

S.Onaka：“通过立体观察确定球形颗粒的纵横比”材料表征。