机械合金化制备Cu—Pb合金粉末的研究

研究了用机械合金化（MA）的方法制备非互溶体系的Cu-Pb合金粉末的机制,对MA过程中粉末的结构、组合形态的变化及Pb的分布进行跟踪分析,实验结果表明,Cu粉和Pb粉经机械合金化后可得到组合均匀、无偏析的合金粉末,为下一步压制、烧结工艺提供了组织保障。     

强流脉冲电子束作用下铝钨合金的表面合金化

将W粉预涂覆在铝基体表面后利用强流脉冲电子束(HCPEB)对其进行合金化处理。利用X射线衍射仪、光学显微镜、扫描电子显微镜及透射电子显微镜详细分析了合金层微观结构。并考察了HCPEB合金化后样品表面的力学性能和耐腐蚀性能。实验结果表明:经HCPEB处理后材料表层发生了合金化,合金化层主要由熔化层和固态扩散层构成,厚度达到15μm左右;合金层的相主要为W和(或)Al-W金属间化合物组成;处理后的样品表面硬度得到显著提高。此外,电化学实验结果表明,合金化后表面耐腐蚀性能也得到明显的改善。     

机械合金化法制备Ti-Zr-Ni-Cu储氢合金

使用行星式球磨机,用机械合金化法制备了Ti60Zr15Ni15Cu10储氢合金.采用X射线衍射仪XRD、示差扫描量热计DSC分析了球磨粉末的物相、晶粒尺寸的变化;采用扫描电子显微镜SEM、能谱EDS分析了机械合金化过程中粉末的形貌和成分;并对球磨粉末进行了P-C-T曲线测量.研究结果表明,粉末晶粒尺寸随球磨时间增加不断减小.球磨120 h粉末含有大量非晶相.粉末颗粒中有明显的冷焊合层状结构.随球磨时间增加,层状结构的层厚不断减小,颗粒中的元素分布趋于均匀,合金化过程中的冷焊合和断裂作用逐渐趋于平衡.合金的最大吸氢量物质的量为1.63%,纳米结构粉末的吸氢量高于非晶结构粉末.     

纳米多孔PtFe和PtFeCu催化剂的制备及其对小分子物质催化性能研究

通过快速凝固法制备Al₉₈Fe₁Pt₁和Al₉₇Fe₁Cu₁Pt₁前驱体合金条带,利用两步去合金化法对其处理最终获得具有不同结构的纳米多孔PtFe和纳米多孔PtFeCu合金。利用扫描电镜(SEM)和透射电镜(TEM)对去合金化后的样品进行表征分析,发现其存在双连续的韧带-通道结构,该结构能够为小分子物质的传输提供通道,增大接触面积。电化学测试结果表明,与商用Pt/C相比,纳米多孔PtFe和PtFeCu合金对甲醇、乙醇、甲酸的氧化反应均表现出更优异的电催化活性,且具有更好的稳定性。     

去合金化制备纳米多孔二元PtCu合金及其催化性能研究

电极材料是质子交换膜燃料电池(PEMFC)应用的关键材料。设计了一种新型的多组分纳米多孔合金电催化剂,并通过调节前驱体合金的成分进一步改善了其电催化性能。采用快速凝固技术与两步去合金化相结合的方法,制备了具有双连续多孔结构的二元Pt₂Cu催化剂。研究结果表明,前驱体合金条带经过两步去合金化处理可获得具有三维双连续韧带通道结构的纳米多孔金属。电化学测试表明,二元Pt₂Cu催化剂比商用PtC催化剂具有更好的催化活性和稳定性,其与Cu合金化可以优化Pt的电子结构,改善催化剂的催化性能。该制备工艺为其他多组分Pt基催化剂的制备提供了有益参考。     

机械合金化制备Mg-Cu非晶合金粉末的机理研究

采用XRD和TEM研究了MgCu2和Mg58Cu42混合粉末在机械合金化过程中的结构变化。结果表明:Mg、Cu粉末在机械合金化过程中是互溶的,机械合金化可以大大提高它们之间的固溶度;球磨过程中,Mg原子逐步溶入Cu基体中,形成Mg在Cu中的过饱和固溶体;固溶体的变形能量积聚到很大时,发生固溶体晶体结构的失稳,最后形成非晶态合金。在相同的球料比的条件下,提高球磨转速,可以大大促进非晶化的形成过程,缩短非晶形成的时间。     

强流脉冲电子束作用下TC4钛合金表面Cr合金层制备及性能

利用强流脉冲电子束技术(HCPEB)对TC4钛合金表面进行Cr合金化处理,从而改善了材料的表面性能。采用X射线衍射(XRD)、金相显微镜(OM)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)分析表层中的相组成和微观结构。试验结果表明:经HCPEB表面合金化后基体表面形成了数微米的Cr合金层,合金层中析出了颗粒细小、均匀分布的Laves相Cr2Ti;同时,TC4钛合金经HCPEB轰击后表层发生了马氏体相变,形成了大量的板条马氏体组织。此外,硬度测试和电化学结果表明:经HCPEB处理后样品的表面显微硬度和耐蚀性能均得到明显提高。     

氧化辅助脱合金法制备Cu_xO多孔纳米结构薄膜

采用课题组新发展的氧化辅助脱合金（OAD）技术,对由磁控溅射设备在不锈钢衬底上沉积的Cu0.54Al0.46合金薄膜进行化学腐蚀处理,从而得到CuxO多孔纳米结构薄膜。利用粉末X射线衍射仪、扫描电子显微镜和透射电子显微镜对腐蚀产物的晶体结构、微观形貌和化学成分进行了表征分析。研究结果表明,腐蚀产物为一大面积且均匀的CuxO多孔纳米结构薄膜,它主要由片状结构的Cu8O7和棒状结构的Cu2O共同组成。进一步地,对CuxO多孔纳米结构薄膜的形成机理进行了初步探讨。     

退火处理对Ti-Zr-Cu-Be块体非晶合金力学性能的影响

采用铜模铸造法制备了直径为2mm的Ti55-xZr10+xBe27.5Cu7.5(x=0,10,20)块体非晶合金,并对其进行等温退火处理.利用X射线衍射(XRD)、扫描电镜(SEM)、差氏扫描量热仪(DSC)及压缩试验等方法研究了非晶合金的相结构、显微组织和热稳定性,以及退火处理对其力学性能的影响.结果表明:该系列合金在553 K及583 K下保温长达5 h时间内依然表现为非晶态.退火处理后,Ti35Zr30Be27.5Cu7.5合金屈服强度、断裂强度均提到了提高,其中在583 K下保温1 h后屈服强度、断裂强度分别达到了1 921、2 169 MPa;其塑性由处理前的3.47%提高到了6.57%.Ti45Zr20Be27.5Cu7.5合金在退火后其力学性能变化不明显.Ti55Zr10Be27.5Cu7.5合金随着退火温度及保温时间的增加其屈服强度、断裂强度及塑性均明显降低.     

机械合金化法制备锂离子电池锡基负极材料及其性能

采用机械合金化技术制备了系列Sn基合金负极材料,并对其结构和性能进行了详细的研究.结果表明,Cu6Sn5-10%Cu样品表现出最佳的循环稳定性,初期容量约为作为300 mAh/g,100周充放电循环后容量仍然保持在200 mAh/g以上.该样品是由Cu6Sn5,Cu3Sn和CuSn三相组成的复合材料,颗粒分布比较均匀,粒径主要在1~2μm之间.在首次充放电过程中由于有机电解液的分解和形成的CuLi2Sn中间化合物的不完全脱嵌,该材料存在较大的首次不可逆容量损失.通过对充放电电位窗口(截至电位)的限制,可以有效的改善合金负极的循环稳定性.     

Effect of annealing on the characteristics of Au/Ni50Fe50 bilayer films grown on glass

Sputter-deposited Au/Ni_(50)Fe_(50) bilayer films were annealed in a vacuum of 5×10~(-4) Pa at 523 to 723 K for 30 or 90 min. The characteristics of the bilayer films were determined by Auger electron spectroscopy, field emission scanning electron microscopy, X-ray diffractometry, a four-point probe technique, and an alternating gradient magnetometer. When the annealing temperature and time reached 723 K and 90 min, Ni and Fe atoms markedly diffused into the Au layer. The grain size of the Au layer did not change markedly with the annealing condition. As the annealing time was 30 min and the annealing temperature exceeded 573 K, the resistance of the bilayer film increased with increasing the annealing temperature. Furthermore, the resistance of the bilayer film annealed at 723 K for 90 min was lower than that of the bilayer film annealed at 723 K for 30 min. All the bilayer films showed magnetic hysteresis loops. The as-deposited bilayer film showed a hard magnetization. The bilayer film represented an easy magnetization with increasing the annealing temperature. The Au/Ni_(50)Fe_(50) film that annealed at 723 K for 90 min had the lowest saturation magnetization.     

Effect of relative density on cyclic oxidation resistance properties of MoSi2

MoSi2 powders were fabricated respectively by mechanical alloying technique and sintering at different temperatures to prepare materials with different relative densities. The relative oxidation behavior of all MoSi2 materials at 1 473 K was investigated by TGA,SEM and XRD. The results show that the ＂pesting＂ is not found in all materials after being oxidized for 480 h. The density has no essential relation to the ＂pesting＂. The oxidation curve of specimens with lower density shows two-step oxidation kinetics. Both the first stage （0-1 h） and the second stage （1-480 h） nearly obey linear kinetics,but the oxidation rates are obviously different. The oxidation kinetics of MoSi2 with higher relative density nearly follows parabolic law. The mass gains of MoSi2 with the lowest relative density （78.6%） and the highest relative density （94.8%） are increased by 10.390 and 0.135 mg/cm^2,respectively. The oxide scale of materials with lower densities is non-protective and makes the oxygen diffusion easy. A dense scale in the material with higher density is formed,which acts as a diffusion barrier to the oxygen atoms to penetrate into the matrix,showing much better high temperature oxidation resistance. The phases distribution of oxidation scale from the outside to the inside is SiO2→Mo5Si3→MoSi2.     

含硼合金化高锰钢鄂板的应用研究

研究了合金化高锰钢鄂板材料的组织、力学性能,分析了其耐磨性,结果表明含硼合金化高锰钢鄂板.寿命较原来的普通高锰钢提高了2.3倍;合金元素B,Cr,RE改善了高锰钢的组织和性能,是颚式破碎机鄂板寿命提高的主要原因;合金化高锰钢的韧脆转变温度为-20℃.     

Effects of heat-treatment on crystallization and wear property of plasma sprayed Fe-based amorphous coatings

The Fe-based amorphous coatings were produced by air plasma spraying. The as-sprayed coatings were heat-treated at the temperature of 573, 873, and 1 023 K, respectively. The crystallization and wear behavior of the heat-treated amorphous coatings were investigated. It was found that the amorphous-nanocrystalline transformation appeared when the as-sprayed coatings were treated at 853 K. The crystallization process had completed and a coating with microcrystallines was formed when the treatment temperature reached 1 023 K. The resultant amorphous and nanocrystalline composite coatings exhibited superior wear resistance compared to crystalline coating. It is attributed to fine grain strengthening of formed nanocrystallines.     

Microstructure and properties of W-15Cu alloys prepared by mechanical alloying and spark plasma sintering process

W-15Cu composite powders prepared by mechanical alloying （MA） of raw powders were consolidated by spark plasma sintering （SPS） process at temperature ranged 1 230-1 300 ℃ for 10 min and under a pressure of 30 MPa. By using high energy milling, particles containing very fine tungsten grains embedded in copper, called composite particles, could be produced. The W grains were homogeneously dispersed in copper phase, which was very important to obtain W-Cu alloy with high mechanical properties, fine and homogeneous microstructure. The microstructure and properties of W-15Cu alloys prepared by SPS processes at different temperature were researched. The results show that W-15Cu alloys consolidated by SPS can reach 99.6 % relative density, and transverse rupture strength （TRS） is 1 400.9 MPa, Rockwell C hardness （HRC） is 45.2, the thermal conductivity is 196 W/m-K at room temperature, the average grain size is less than 2 μm, and W-15Cu alloy with excellent properties, homogeneous and fine microstructure is obtained.     

镍基喷涂层抗焦粒冲蚀磨损性能的研究

在干熄焦余热锅炉中，焦位微尘对过热器管有冲蚀磨损作用，为提高过热器管的使用寿命，在１５ＣｒＭｏ过热器管表面热喷涂镍基合金．本文通过６７３～８７３Ｋ氧化试验和焦粒的室温冲蚀磨损试验，比较１５ＣｒＭｏ钢喷涂镍基合金前后的抗氧化能力和冲蚀磨损抗力。试验结果表明，镍基合金喷涂层的抗氧化能力和抗焦粒冲蚀磨损的性能均大大优于１５ＣｒＭｏ钢。     

Nb—V球铁作为轧辊材料及其断裂韧性研究

采用正交试验方法寻找Ｎｂ,Ｖ等合金元素与变质剂的最佳组合以获性能良好的球铁轧辊材料,比较Ｎｂ－Ｖ球铁与Ｎｉ－Ｍｏ球铁试样断裂韧性值ＫＩＣ,结果表明,Ｎｂ－Ｖ球铁试样具有足够的韧性,不致引起裂纹失稳扩展,可代替Ｎｉ－Ｍｏ合金元素生产球铁轧辊。     

New Mg<Subscript>2</Subscript>Si based alloy for automobile engine cylinder liner

New Mg₂Si based alloy were prepared by mechanical alloying. Sintering temperature was from 825 to 865K, which indicated that few Mg₂Si were produced at lower temperature while MgO were produced at higher temperature. Microstructure image showed that at sintering temperature of 855K, Mg₂Si were mostly synthesized with the reaction of purity magnesia powder and silicon powder. Hardness and wear tests proved that the new synthetic silicon magnesium alloy had higher hardness and good wear resistance. Under the same testing conditions, it is found that the hardness of the new material is 420.50, and pure magnesium is only 41.65.In the same experiments it is also found that under the same pressure, pure magnesium alloys than silicon wearing capacity of pure magnesium is 2 times as high that of Mg₂Si based alloy. It shows that Mg₂Si based alloy is the ideal material for the wear parts of car engine cylinder liner because of its small density, stable dimension, high hardness and wear-resisting.     

Deformation temperature and postdeformation annealing effects on severely deformed TiNi alloy by equal channel angular extrusion

Micron TiNi alloy blocks were fabricated at high temperature by equal channel angular extrusion (ECAE) using hot-forged Ti-50.3at%Ni alloy as the raw material and the effects of deformation temperature and postdeformation annealing on the severely deformed TiNi alloy by ECAE were investigated. The results show that the TiNi alloy processed by ECAE undergoes severe plastic deformation, and lowering the deformation temperature and increasing the number of extrusions contribute to grain refine- ment. When the annealing temperature is below 873 K, static recovery is the main restoration process; when the temperature rises to 973 K, static recrystallization occurs. It is found that fine particles are precipitated when the TiNi alloy processed by ECAE is an- nealed at 773 K.     

Preparation and properties of FeZrB amorphous-nanocrystalline soft magnetic alloy

Fe₆₈Zr₂₀B₁₂ amorphous alloy was prepared by mechanical alloying(MA) method and annealed at different temperatures. Microstructures and magnetic properties of Fe₆₈Zr₂₀B₁₂ alloys as-milled and annealed at 693, 843, 943 and 993 K were studied. The raw powders(Fe, Zr, B) formed b. c. c. α-Fe solid solution at early stages of MA and then transformed into amorphous alloy. Grain size(D) of Fe₆₈Zr₂₀B₁₂ alloys increases with increasing annealing temperature and keeps at nanometer level. The specific saturation magnetization(σ _s ) increases with increasing annealing temperature from 300 K to 943 K, and then decreases with annealing temperature at 993 K because of the precipitation of Fe₃B.