室温磁致冷合金Pr2Fe17-xCox的结构、磁性和磁熵变

在氩气气氛中用熔炼法制备了Pr2Fe17-xCox系列合金，通过粉末X射线衍射和SQUID磁强计研究了样品的结构、磁性和磁熵变。结果表明：Pr2Fe17-xCox系列合金具有菱方Th2Zn17型结构；通过成分微调使其居里温度处在室温附近：Pr2Fe17-xCox，系列合金有较大的磁熵变，在低场下的磁熵变是金属Gd的65％～73％，而高场下的磁熵变则为金属Gd的63％～68％；但其成本约为金属Gd的1／10，具有很高的性价比，是一类有很大应用潜力的室温磁致冷材料。     

热塑性塑料注塑件熔接缝影响因素分析

分析了热塑性塑料注塑件中熔接缝的分类和特征。从材料选择、制品结构设计、模具设计、成型工艺、热处理几个方面分析了影响熔接缝的因素;并针对不同因素,提出了相应的对策和改善熔接缝力学性能的方法。     

Pr对Sn58Bi钎料微观组织和性能的影响

通过在Sn58Bi合金钎料中添加Pr制备了新型无铅钎料,用该钎料进行焊接后,测定了Pr添加量对焊后钎料的晶格变化、润湿性和钎焊接头抗拉强度的影响。XRD衍射结果表明,Pr的添加能够导致钎料晶格畸变。SEM结果表明,微量Pr的添加可以抑制Bi相长大粗化,细化钎料晶粒。润湿性能研究表明,随着Pr量的增加,Sn58Bi 钎料的润湿性有所改善,当添加质量分数为1.5% 的Pr时,钎料的铺展率由81.97%扩大到88.41%,增加了7.86%;钎料力学性能显示,未添加Pr时钎焊接头抗拉强度为7.631 8 MPa,而随着Pr的加入,其抗拉强度增加,当添加质量分数为1.5%的Pr,钎焊接头抗拉强度最大为11.126 3 MPa,提高了45.79%。综合表明,适量Pr的添加可以有效改善Sn58Bi钎料的组织结构、润湿性和抗拉强度。创新点： (1)添加微量稀土元素制备Sn58BiPr无铅焊料。(2)Pr的掺入可使焊料晶格畸变、细化焊料晶粒。(3)添加Pr能有效改善焊料的润湿性和抗拉强度。     

Fantastic valence impacts of Pr on microstructures and Faraday magneto-optical effects of transparent (Ho,Pr)2O3 ceramics

Polycrystalline magneto-optical (Ho_1-xPr_x)₂O₃ (x = 0.05?0.2) ceramics were fabricated by vacuum sintering using layered rare-earth hydroxides as the precursors, among which the 5 at.% Pr doped specimen exhibits the highest in-line transmittance of ～76.1 % at 700 nm (～94.5 % of the theoretical value of defect-free Ho₂O₃ single crystal) and the largest Verdet constant of ?82 ± 6 rad?T^?1 m^?1 at 1064 nm (～2.3 times that of the commercial Tb₃Ga₅O₁₂ crystal and ～1.8 times that of the pure Ho₂O₃ ceramic). More Pr addition not only leads to a higher thermal decomposition temperature for the precursor but also a decreasing particle size for the oxide. A 5 at.% Pr dopant in Ho₂O₃ matrix generally exists in the oxidation state of +3, while an increasing Pr concentration up to 10 at.% induces coexisting valences of +3 and +4. The grain growth was suppressed by the present Pr⁴⁺ based on interstitial mechanism. The substitution of Pr³⁺ for Ho³⁺ is helpful for the rising Verdet constant of the binary ceramic, but Pr⁴⁺ has little positive contribution to it.     

Isothermal Section of Phase Diagram of the Ternary System Co-Dy-Pr at 500℃

１ＩｎｔｒｏｄｕｃｔｉｏｎＲｅｆ．１,２ｒｅｐｏｒｔｅｄｔｈｅｓｔｕｄｙｒｅｓｕｌｔｓｏｆＣｏＰｒｂｉｎａｒｙｓｙｓｔｅｍ．Ｔｈｅｙｏｂｓｅｒｖｅｄｔｈｅｅｘｉｓｔｅｎｃｅｏｆｎｉｎｅｉｎｔｅｒｍｅｔａｌｉｃｃｏｍｐｏｕｎｄｓ,Ｐｒ２Ｃｏ１７,...     

SnCuNi-xPr焊点组织和性能分析

分析了不同稀土元素Pr的添加量对Sn0.7Cu0.05Ni无铅钎料润湿性能、焊点力学性能以及钎料显微组织的影响,并对焊点内部组织的演化规律与其性能之间的内在联系进行了初步探讨.研究发现,稀土元素Pr的适宜添加量为0.025%～0.075%,且存在一最佳添加量0.05%.微量稀土元素Pr的加入可显著降低液态钎料的表面张力...     

PDM及其在企业中的作用

分析了现代企业在应用CAX技术提升企业功能的同时所遇到的问题,重点介绍PDM技术及其在现代企业中的作用。     

非晶Pr8Fe86B6合金的晶化动力学

用差热分析（DTA），结合X射线衍射（XRD）研究了非晶Pr8Fe86B6合金的晶化动力学。结果表明：该非晶Pr8Fe86B6合金的晶化相为α－Fe固溶体和Pr2Fe14B金属间化合物，通过对两相晶化激活能的分析得出：α－Fe相的激活能在晶化初期变化不大，当其体积分散大于8％时，其晶化激活能开始减小，而Pr2Fe14B相的激活能随其体体积分数的增加而减小，且α－Fe相较Pr2Fe14B相容易易化析出。     

(Zn, Ca) Solid-Solution Behavior and Its Effect on Luminescence Properties in Ca1- xZnx TiO3: 0.002Pr3+ Phosphors

Nominal composition of Ca1 - xZnxTiO3: 0. 002Pr3 ( x = 0. 000 ～ 0. 200) phosphors were prepared by conventional solid reaction route. XRD and PL measurements were used to investigate the solid-solution structure and luminescence properties of Zn-doped Ca1- xZnxTiO3:0. 002Pr3 phosphors. The effect of solid-solution structure formed by substitution between Ca2 and Zn2 ions on the luminescent properties was analyzed. The results reveal that, with the increase of Zn substitution content below 0.010, lattice parameters and the intensity of excitation peak at both 260 and 330 nm as well as the corresponding 610 nm emission intensity are monotonously decreased quickly in a similar tendency. Also, the evolution of luminescence intensity and crystal cell parameters against Zn doping concentration are in good agreement.Above results are closely related with the structure change within Ca1- xZnxTiO3:0. 002Pr3 solid-solution phase formed by the Zn ions substitution for the Ca sites. Present study reveals that the solid-solution structure formed by substitution between Ca2 and Zn2 ions has significant effect on the luminescence properties of single phase Ca1- xZnxTiO3:0.002Pr3 phosphors.