NiTi 形状记忆合金由于热弹性马氏体相变而表现出优异的超弹性和形状记忆效应,被广泛应用在医疗器械、航空航天等领域.采用激光定向能量沉积工艺制备Ni50.8Ti形状记忆合金,通过室温压缩实验和循环压缩实验分析成形角度对合金超弹性及其稳定性的影响规律,借助X射线衍射分析、电子背散射衍射等表征手段分析不同成形角度合金的微观组织和织构特征,进而深入研究微观组织和织构对Ni50.8Ti形状记忆合金超弹性及其稳定性的影响.结果表明:采用激光定向能量沉积制备的Ni50.8Ti形状记忆合金由B2 奥氏体相组成,基体成分均匀,无开裂现象.与Y轴呈 90°的合金在室温下呈现出最佳的超弹性,0°的合金超弹性最差.同时,45°的合金呈现出强〈112〉织构,90°的合金呈现出强〈110〉织构,强织构合金的超弹性比弱织构(60°)和不利取向(0°)合金的超弹性更好,织构对于 Ni50.8Ti 形状记忆合金的微观组织和超弹性具有显著的影响.
Effect of texture on the superelasticity of Ni50.8Ti shape memory alloy for laser directed energy deposition
NiTi shape memory alloy exhibits excellent superelasticity and shape memory effect due to thermoelastic martensitic phase transformation,and is widely used in medical devices,aerospace and other fields.Ni50.8Ti shape memory alloy was prepared by laser directed energy deposition,the influences of forming angle on the superelasticity and stability of the alloy were analyzed by room temperature compression and cyclic compression experiments,the microstructure and texture characteristics of alloys with different forming angles were analyzed by X-ray diffraction analysis,electron backscatter diffraction and other characterization methods,and the influences of microstructure and texture on the superelasticity and stability of Ni50.8Ti shape memory alloy were further studied.The results show that the Ni50.8Ti shape memory alloy prepared by laser directed energy deposition is composed of B2 austenitic phase with uniform matrix composition and no cracking phenomenon.Alloy at 90° Y-axis shows the best superelasticity at room temperature,and the worst superelasticity at 0°.At the same time,the 45° alloy shows a strong 〈112〉 texture and the 90° alloy shows a strong 〈110〉 texture,the superelasticity of the strong texture alloy is better than that of the weak texture(60°)and the unfavorable orientation(0°)alloy,the texture has a significant influence on the microstructure and superelasticity of the Ni50.8Ti shape memory alloy.
additive manufacturingdirected energy depositionNiTishape memory alloytexture
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