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Electrochemical behaviors of laser-welded Ti-50.6%Ni(mole fraction) shape memory alloy and the base metal in 0.9% NaCl solution were investigated by electrochemical techniques as corrosion potential measurement, linear and potentiodynamic polarization. The results indicate that the laser-welded NiTi alloy is less susceptible to pitting and crevice corrosion than the base metal, which is demonstrated by the increase in polarization resistance(Rp) and pitting potential(φpit) and decrease in corrosion current density(Jcorr) and mean difference between φpit and φprot values. It is confirmed by scanning electron microscope micrographs that pits could be observed on the surface of base metal but not on the surface of laser-welded alloy after potentiodynamic tests. An improvement of corrosion resistance of laser-welded NiTi alloy could be attributed to almost complete dissolution of inclusions upon laser welding. 相似文献
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超弹性NiTi合金丝激光点焊接头的组织和性能 总被引:4,自引:2,他引:4
采用脉冲激光焊研究了Ti-50.6%Ni(摩尔分数)合金细丝点焊,对比分析了接头与母材显微组织、相变行为、Ni含量、显微硬度及应力-应变曲线的变化.结果表明:当NiTi合金用做功能材料时,激光焊接是可取的;激光点焊接头熔化区由树枝晶组成,热影响区靠近熔池部分为粗大等轴晶,靠近母材部分为细小等轴晶;激光焊会造成Ni的蒸发,使接头中Ni含量降低0.2%(摩尔分数),从而影响接头的相变行为;接头抗拉强度可达母材的70%,可恢复应变达母材的92%. 相似文献
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通过用手持GPS对长春市城区25块街区的测量面积与1:500地形图上同名地块面积的比较,得出当地块面积大于10万m2时,手持GPS-次测量的面积精度为0.32%~0.56%,平均为0.51%;通过回归分析技术对手持GPS测量的面积进行改正,所测面积的平均精度可提高到0.3%. 相似文献
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为了研究热循环对NiTi合金激光焊接接头相变行为的影响,用激光点焊了φ0.5 mmTi-50.6%Ni合金细丝,利用金相显微镜观察了母材和接头的显微组织,通过示差热分析仪研究了热循环对点焊接头相变行为的影响.结果表明,NiTi合金激光点焊接头,熔化区为树枝晶,热影响区由粗大等轴晶和细小等轴晶组成.热循环可改变接头的相变行为,使马氏体相变由B2→B19'转变为B2→R→B19'.随着热循环次数的增加,正相变过程中Rs点升高,R相变温度范围变宽,Ms点降低;逆相变的相变温度都降低. 相似文献
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船用柴油机进气消声器的研制 总被引:1,自引:0,他引:1
船用柴油机为提高功率装有进气增压装置,在装有增压装置提高发动机吸气系数同时会产生频率很高很大的噪音,进气消声器是一种既能允许气流顺利通过,又能有效地阻止或减弱噪音向外传播的装置。 相似文献
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