添加微量稀土元素对Sn-Ag-Cu系无铅焊料性能的影响

以Sn-3．0Ag-0．5Cu（质量分数，％）焊料为母合金，探讨了微量稀土元素Ce、Er、Y和Sc对Sn—Ag—Cu合金物理性能、润湿性能以及力学性能的影响。试验结果表明：稀土元素对焊料的性能有不同的影响，添加微量Ce元素可以更好地改善焊料综合性能。     

稀土Ce对耐磨钢NM400性能的影响

采用转炉初炼→LF精炼→RH精炼→轧钢→淬火→回火工艺实验生产含稀土Ce耐磨钢NM400,通过调整精炼过程中稀土Ce的添加量,研究不同含量稀土Ce对钢板力学、磨损及耐腐蚀性能的影响。结果表明：添加稀土Ce后耐磨钢NM400的冲击和磨损性能均得到提升;随着稀土Ce含量的增加,钢板在模拟矿井液腐蚀环境中的耐腐蚀性能提高,添加0.006 0%稀土Ce比未添加稀土Ce钢板的耐腐蚀性能提高21.8%。     

镁合金的锻造(续)

MA8合金，除含有0．15％-0．5％Ce外，其余化学成分与MAl合金相同。显微组织如图5所示，由Mg的固溶体晶粒与锰的质点组成，与MAl合金相同。添加Ce可以细化晶粒，因而MA8合金的力学性能比MAl合金高。不过，由于铈的含量少，且与镁形成的Mg9 Ce化合物质点弥散地分布于固溶体中，通常在显微镜下观察不到。     

稀土元素铈对镁合金AZ91D显微组织和力学性能的影响

利用光学显微镜、X射线衍射和扫描电镜等分析研究含铈镁合金AZ91D（0．25％Ce、0．7％Ce、0．95％Ce）的显微组织,并对其力学性能进行了测试,同时与不含铈镁合金AZ91D进行了比较。结果表明,加入一定量Ce后的镁合金AZ91D形成杆状化合物Al4Ce,被推移到生长界面,阻碍枝晶的自由生长,从而细化合金显微组织;Ce能提高镁合金AZ91D抗拉强度和硬度,而对其屈服强度和延伸率影响不大;加入0．7％Ce的AZ91D镁合金晶粒细化效果和综合力学性能比较理想。     

Ce对A356合金的影响及细化机制的研究

研究了Ce对A356铝合金晶粒细化的效果以及对其力学性能的影响。结果表明:在未添加稀土Ce时,A356铝合金结晶时,其中的初生相α-Al呈现为粗大的树枝状。在添加不同量的稀土Ce时,A356铝合金中的初生相α-Al明显得到细化,树枝状晶转化为等轴晶。在Ce合金添加量为0. 1%时其细化效果最好,α-Al的等效直径和形状因子均达到最优水平,分别为24. 5μm和0. 61;二次枝晶臂间距最小,平均二次枝晶臂间距为14. 63μm;其力学性能也达到最佳,抗拉强度和延伸率分别为165. 89 MPa和3. 5%,合金的硬度为HV 77. 6。添加量超过0. 1%时,其细化效果会随着添加量的增加而逐渐减弱。稀土Ce对于合金晶粒细化比较符合异质形核理论,Al-Ce中间合金中的Al11Ce3和α-Al具有相似的晶体结构,而且晶格常数也能与之相对应。在A356合金液中添加Al-Ce中间合金时,Al11Ce3粒子作为A356合金凝固时的异质形核点从而促进细化。     

铈对铸造镁合金AZ91D显微组织与力学性能的影响

利用光学金相显微镜OM和XRD分析了分别加入0．1％，0．3％，0．5％，0．7％和1．0％Ce的AZ91D合金显微组织和相组成，测试了室温力学性能和硬度。结果表明，加入一定量Ce后的AZ91D合金形成杆状化合物Al4Ce，被推移到生长界面，阻碍枝晶的自由生长，从而细化合金显微组织；Ce能提高AZ91D合金室温抗拉强度和硬度，而对其屈服强度和延伸率影响不大；加入0．7％Ce的AZ91D合金晶粒细化效果好，其综合力学性能比较理想。     

黄褐土添加稀土对可溶态稀土含量和油菜生长的影响

在黄褐土上分别进行了添加La,Ce和Nd(REO添加量为0、300、600、1200、1800mg/kg)的试验。结果表明稀土添加量与土壤可溶态稀土含量的变化、土壤可溶态稀土含量与油菜体内的稀土含量、油菜体内的稀土含量与油菜的生长量之间均呈明显的相关性。La,Ce和Nd在一定浓度范围内对油菜的生长均有明显的作用。     

残余Ca和残余Ce含量对UNS N06600合金塑性影响

详细分析了残余Ca、残余Ce含量对UNSN06600合金热加工塑性的影响,通过大量实践证明,残余Ca含量控制在0．0008—0．0018％范围内、残余Ce含量控制在0．01％～0．02％范围内,热加工塑性良好。     

Cu、Ni、Zn、Mn系弹性合金形变热处理的研究

研究了微量元素及形变热处理工艺对Cu－15Ni－13Mn－28Zn弹性合金微双相化的影响。结果表明;冷变形量增加,可缩短微双相化时间;添加微量元素①0．187Al＋0．013Ce＋0．24Fe＋0．1B＋0．1Ti＋0．1Zr,②0．5Ti可缩短微双相化时间;在时效过程中,α相点阵常数初期随时间延长而下降,微及相化完成后则随时间延长而上升。     

微量稀土Ce对金合金铸态组织及其硬度的影响

文中研究了微量稀土元素Ce在金合金中的分布情况,观察了稀土元素Ce不同添加量对金合金铸态组织及其硬度的影响.研究发现:在添加Ce的金合金中,Ce部分固溶,部分作为异质点Ce-Si化合物存在,基本没有Ce的偏聚;添加0.075?金合金铸态组织就可以达到较好的晶粒细化效果,分析其作用机理是添加Ce的金合金以高熔点的Ce-Si化合物和氧化物作为异质点,起到异质晶核的作用而细化组织;在低于Ce的金合金固溶度时,铸态合金的硬度随Ce含量增加而升高,过量Ce对金合金的铸态硬度影响不大;利用时效处理,能显著地提高金合金的硬度,Ce主要强化机制在于固溶强化.     

微量Ce对细化A356合金初生相的作用

利用低过热度浇注技术制备了半固态A356-Ce合金浆料,研究了稀土Ce对半固态A356合金的初生相形貌和尺寸的影响.研究结果表明:含有适量稀土Ce的A356铝合金经低过热度浇注可制备具有颗粒状和蔷薇状初生相的半固态浆料,合金熔体等温温度会影响Ce细化半固态A356合金中初生相的效果.Ce对半固态A356铝合金的初生相细化机理与稀土在铝合金中诱发的共晶反应有关.      

工艺参数对熔配法制备Al-10Ce中间合金的影响

用熔配法制备了Al-10Ce中间合金,采用X射线衍射相分析(XRD)等技术对Al-10Ce中间合金的相组成进行了分析,试验结果表明:Al-10Ce中间合金由Al、Ce、Al4Ce三相组成。且通过试验从熔体温度、溶解时间、搅拌方式等三方面分析了用熔配法制备Al-10%Ce中间合金的工艺参数,确证了参数选择的可行性和合理性。     

微量稀土对铸态Cu-3.0Si-2.0Ni合金组织及性能的影响

加入适量的稀土元素能有效改善铜合金的组织和性能.铸态Cu-3.0Si-2.0Ni合金中添加稀土Ce后,进行熔炼及热处理试验,再通过室温拉伸、导电率试验和金相观察,研究了微量Ce对铸态Cu-3.0Si-2.0Ni合金组织与性能的影响.结果表明:铸态合金晶粒随着Ce含量的升高呈现先减小后递增的趋势;铸态合金的抗拉强度和导电性随着Ce的增加分别先升高后减低;当Ce的质量分数为0.06%时,铸态合金的抗拉强度最高、导电性最强.     

The effect of rare earths on the solidification structure of Fe-36Ni invar alloy

The effect of Ce,La and mischmetal on the solidification structure of Fe-36Ni invar alloy was investigated.The results show that great amounts of high-melting point compounds (Ce2O3,La2O2S and (Ce,La)2O2S) respectively formed in the alloy with the addition of Ce,La or mischmetal.Based on the theory of lattice misfit,the lattice misfit between the (0001) surfaces of Ce2O3,Ce2O2S and La2O2S and (100) surface of Fe-36Ni invar alloy were 6.21%,5.77% and 5.42%,respectively,which are relatively low.Therefore,Ce2O3 ,La2O2S and (Ce,La)2O2S could serve as the core of heterogeneous nucleation,improve the equiaxed grain ratio,reduce the equiaxed grain size and refine the solidification structure of alloy.     

V-Ti-Fe储氢合金的真空精炼

采用真空感应炉对金属热还原法制备的V-Ti-Fe合金进行精炼,考察金属铈对精炼效果的影响。结果表明,铈可有效脱除合金中的氧杂质,减少合金内的富钛相和硅偏聚相,降低合金的成分偏析,促进合金的吸氢活化。随铈用量的增加,脱氧效果也逐渐增强,储氢容量得到提升,当铈添加量达到合金用量的5%时,氧含量降到了0.05%,最大吸氢量和有效放氢量分别达到3.36%和1.85%。     

Microstructure, tensile and creep properties of as-cast Mg-3.8Zn-2.2Ca-xCe（x=0, 0.5,1 and 2 wt.%） magnesium alloys

The microstructure and mechanical properties of as-cast Mg-3.8Zn-2.2Ca alloy with different Ce contents were investigated by both optical and electron microscopy, X-ray diffraction, differential scanning calorimetry analysis, tensile and creep tests. The results indi-cated that adding 0.41 wt.%-1.83 wt.% Ce could refine the grains of the alloy, and the grain size gradually decreased as the Ce content in-creased. Furthermore, addition of either 0.41 wt.% or 0.89 wt.% Ce caused the morphology of the Ca2Mg6Zn3 phase to change partially from semi-continuous block to discrete fine particles. However, after adding 1.83 wt.% Ce, portions of the Ca2Mg6Zn3 and Mg12Ce phases were mixed and this Ca2Mg6Zn3+Mg12Ce eutectic changed to a different coarse semi-continuous morphology. In addition, addition of 0.41 wt.%-1.83 wt.% Ce improved the tensile and creep properties of the alloy. Amongst these Ce-containing alloys, the alloy with 0.89 wt.% Ce exhibited the best ultimate tensile strength and elongation while the alloy with 1.83 wt.% Ce had the best yield strength and creep properties.     

Investigation of Formation and Inhibition Mechanism of Cerium Conversion Films on Al 2024 Alloy

To study the mechanism of formation and inhibition of Ce conversion films on A1 2024-T3 alloy, scanning microreference electrode technique (SMRE) is used to probe the potential map on A1 2024-T3 in CeC13 solution, the localized corrosion of A1 alloy decreases with immersion time and disappears finally, which results from the competition of Cl^- aggression and Ce^3 inhibition on alloy surface. The results of X-ray photoelectron spectroscopy (XPS) indicate that the Ce conversion films consist of Al2O3, CeO2 and Ce2O3 (Ce(OH)3), and CeO2/Ce2O3 ratio decreases with the immersion time. When a critical pH for Ce(OH)3 formation was reached, Ce(OH)3 will precipitate on the micro cathodic area on alloy surface. Consequently, H2O2, the product of the catholic reaction will oxidize a part of Ce(OH)3 to CeO2, which appears a better corrosion resistance for Al alloys.     

Effect of Cerium on Gas Evolution Behavior of Pb-Ca-Sn Alloy

Hydrogen and oxygen evolution reactions areharmful to the valve regulate lead acid battery duringcharging and discharging processes.Oxygen evolutionreaction occurs at the positive electrode in the leadacid battery and transfers from baffle to the negativeelectrode,reducing to water finally.Hydrogen evolu-tion reaction takes place occasionally on the negativeelectrode inthe lead acid battery.In general,the rateof hydrogen oxidation reaction on the negative elec-trode is lower or less hydrogenis…     

Computer Aided Cooling Curve Analysis and Microstructure of Cerium Added Hypereutectic Al–Si (LM29) Alloy

Thermal analysis of LM29 alloy and Ce added LM29 alloys was carried out. The effect of cerium addition on solidification parameters and microstructural features of hypereutectic Al-Si (LM29) alloy was studied using Newtonian analysis technique. Thermal analysis parameters such as primary and eutectic phase nucleation and solidus temperatures were determined. The addition of Ce to LM29 alloy decreased the nucleation temperature of primary silicon and eutectic silicon. The microstructural examination of Ce added LM29 alloys revealed the presence of a polyhedral shaped Al–Si–Ce compound that might have caused the refinement of primary and eutectic silicon. The dendrite coherency point temperature of LM29 alloy was found to be suppressed on addition of Ce.