Fe78B13Si9纳米晶合金的热性能研究

采用适当的热处理工艺将相同成分的Fe_(78)B_(13)Si_9非晶态合金条带晶化制备成纳米晶合金;测定并研究了纳米晶合金的微观结构(晶体结构及尺寸)和一些结构敏感性能(热膨胀、比热),同时,将其与同样成分的非晶态、大晶粒状态合金的性能进行比较分析,认为由于纳米晶合金特殊的微观结构(短程无序),使其在性能上表现出与通常材料有很大差异。     

钕含量对Mg-Cu-Nd非晶合金贮氢性能的影响

通过溶体快淬成功制备了（Mg65Cu25）100-xNdx（x=2，5，7，10）非晶／纳米晶贮氢合金，利用透射电镜、x射线衍射仪和差热分析仪研究了合金的微观组织结构及其热性能，采用ARBINBTW-2000型电池测试仪研究了合金的贮氢性能。结果表明：随着钕含量的增高，合金的贮氢量呈现上升趋势。非晶（Mg65Cu25）93Nd7合金具有最好的贮氢动力学性能和贮氢容量，最高贮氢量达到3．O％（质量分数），而纳米晶（Mg65Cu25）98Nd2具有最低的贮氢动力学性能和贮氢容量。研究还表明，随着钕含量的增高，合金的非晶形成能力增强，非晶的这种独特的短程有序结构是提高贮氢性能的主要因素。     

超音速火焰喷涂制备钼基非晶纳米晶涂层的研究

利用超音速火焰喷涂(HVOF)技术，在0Cr13Ni5Mo不锈钢基体上成功的制备出了一种Mo基非晶纳米晶复合涂层。这种涂层组织均匀致密，孔隙率小，约为3．4％，呈典型的层状分布；涂层是由非晶和纳米晶组成，在非晶基体中均匀分布了纳米晶粒。根据衍射峰的半高宽，计算出Mo基涂层中的晶粒平均尺寸为25～70nm，与通过透射电镜的观察得到晶粒大小数20～70nm相符；涂层具有较高的硬度，平均显微硬度为859．0HV50；所获得的非晶纳米晶涂层具有较高的热稳定性，在1020．1℃以下使用，不会发生晶型转变。     

Selective dissolution of amorphous and nanocrystalline Zr2Ni

Rapidly quenched Zr₂Ni amorphous and nanocrystalline ribbons were subjected to electrochemical selective dissolution. The porous structure of the dealloyed materials showed a dependence on the alloy microstructure. The etching takes place with constant rate in three dimensions, indicating a surface controlled dissolution process. The etching rate of the amorphous alloy was found to be lower than for the nanocrystalline material. Partial crystallization of the de-alloyed amorphous ribbon has been observed. The electrocatalytic activity for Hydrogen evolution reaction of the selectively dissolved amorphous and nanocrystalline ribbons was found to be improved compared to the as-cast alloys.     

纳米晶(Ag-Cu28)-25Sn合金粉末的制备及表征

采用机械合金化法制备纳米晶(Ag-Cu28)-25Sn合金粉末.用X射线衍射(XRD)仪、扫描电镜(SEM)、高分辨透射电镜(HRTEM)和差示扫描量热分析仪(DSC)等分析手段,对合金化过程中物相组成、微观结构及熔化特性进行表征.结果表明:(Ag-Cu28)-25Sn纳米晶合金粉末的物相组成为Cu3Sn和Ag4Sn.球磨 40 h,合金化完全,其熔化温度为548.5 ℃;球磨至60 h,合金明显非晶化,其熔化温度为554.0 ℃,熔程变小且在186.3和399.5 ℃处出现明显放热峰.HRTEM表明,纳米晶的尺寸约为5～10 nm,合金中有非晶态物质出现和晶格缺陷产生.200和400 ℃退火后,合金的平均晶粒尺寸分别为21.3和33.9 nm.     

等温热处理对Zr57Cu15．4Ni12．6Al10Nb5块体非晶合金的组织结构与压缩性能的影响

对Zr57Cu15．4Ni12．6Al10Nb5块体非晶合金进行了等温热处理，用X射线衍射仪、扫描电镜、显微硬度计与压缩试验机研究了不同温度下的等温热处理后合金的组织结构变化、硬度变化与压缩性能变化。该非晶合金出现晶化的温度随热处理时间的增长而降低。在热处理时间相同的条件下，随热处理温度升高，合金的显微硬度有增大趋势。当非晶合金出现相分离或晶化时，其抗压缩强度将急剧下降，断裂方式由非晶态的断裂方式向晶态的断裂方式转变。     

Corrosion behavior of nanocrystalline (Ni70Mo30)90B10 alloys in 0.8 M KOH solution

Nanocrystalline materials are claimed to exhibit improved properties as a result of their novel microstructure. The corrosion behavior of nanocrystalline (Ni₇₀Mo₃₀)₉₀B₁₀ alloys prepared by crystallization from the amorphous state was studied and compared with that of their amorphous and coarse-grained counterparts. Special emphasis was given to the relationship between microstructure and corrosion resistance. It was concluded that nanocrystalline (Ni₇₀Mo₃₀)₉₀B₁₀ alloys are less sensitive to corrosion in alkaline solutions than the coarse-grained material. This behavior was related to their small grain size and homogeneous single phase microstructure. They provide a uniform substrate where it is easy to form a passive film, consisting essentially of Ni(OH)₂ for the alloy studied.     

工艺参数对静液挤压2024铝合金纳米晶组织性能的影响

实验研究了以快速凝固和机械合金化复合工艺制备的２０２４ 铝合金纳米晶粉末为原料, 采用热静液挤压工艺在不同挤压工艺条件下固结成形的挤压态材料的显微组织与力学性能, 探讨了作为主要工艺参数的挤压温度和挤压比对材料组织性能的影响规律及其原因。在此基础上, 进一步确定了２０２４ 铝合金纳米晶粉末热静液挤压固结成形时的挤压温度与挤压比的合理取值范围     

Environmental properties of Zr-based metallic glasses and nanocrystalline alloys

Zr-Cu-Ni-Al belongs to the best glass forming systems known; these glasses are suitable as precursor material for nanocrystalline alloys. For an application as hydrogen storage materials for example it is of great interest to know more about these metastable materials in regard to their environmental properties. Corrosion as studied by a salt spray test or anodic polarization in aqueous solutions exhibit a rather high sensitivity with no significant differences between the amorphous and nanocrystalline state. Hydrogen charging was performed electrochemically in a glycerine-phosphoric acid electrolyte. In Zr-Cu-Ni-Al alloys absorption kinetics and storage capacity were found to be very similar for the amorphous and the nanocrystalline phase. In the nanocrystalline alloy consisting mainly of a fcc (big cube) phase with a NiTi₂ type structure a hydrogen induced amorphization was observed. Oxidation of metastable Zr-based materials in air was studied below the glass transition temperature at 360°C by thermogravimetry. Oxidation resistance was found to improve very significantly from the amorphous to the nanocrystalline microstructure. The scales formed on both materials consist mainly of columnar ZrO₂ with diameter in the nanometer range; Probably including the other metals as a nanocrystalline solid solution.     

FeCuMoSiB合金穆斯堡尔谱研究

用Ｘ射线衍射技术和穆斯堡尔谱技术，研究了Ｆｅ７３．５ＣｕＭｏ３Ｓｉ１３．５Ｂ９合金的结构和超业细相互作用。该合金的相组成为α－Ｆｅ（Ｓｉ）纳米晶和边界相即五余非晶相。典型纳米晶状态下的穆斯堡尔谱由５条亚谱构成，其中４条亚谱为６峰谱，对应α－Ｆｅ（Ｓｉ）相中的４种不同环境的Ｆｅ原子。另１条亚谱对应边界处的非晶相，研究了非晶带材经５００－６００℃不同温度晶化处理后的穆斯堡尔谱特性。     

等温退火对Ni-P、Ni-W-P镀层的晶粒尺寸和显微硬度的影响

研究了不同镀态结构的Ni-P、Ni-W-P镀层经等温退火后，其晶粒尺寸和硬度随退火时间的变化规律，镀层的热稳定性以及成分、结构和晶粒尺寸对镀层硬度的影响规律。结果表明，W元素可以促进Ni-P合金的非晶化，显著提高Ni-P镀层的硬度；Ni-（W）-P体系纳米晶镀层具有较好的热稳定性；等温退火获得的三元Ni-W-P单相纳米晶镀层在耐磨、耐蚀性能方面均优于同类非晶态镀层。     

Plastic flow of a nanocrystalline/amorphous Al90Fe5Gd5 composite formed by rolling

Mechanically induced nanocrystallization has attracted much interest and is expected to be an alternative route for synthesizing nanocrystalline/amorphous matrix composites. However, little research has been performed on the mechanical behavior of these composites. Using nanoindentation, we have investigated plastic flow of a nanocrystalline/amorphous Al₉₀Fe₅Gd₅ composite produced by rolling at room temperature. The nanocrystalline/amorphous matrix composite exhibits less-obvious serrations than the as-spun amorphous alloy. Using high-resolution transmission electron microscopy and atomic force microscopy, we observed the microstructure and morphology of indents. It is believed that the predominant deformation mechanism in the nanocrystalline/amorphous composite is the propagation of preexisting shear bands, in contrast to nucleation and propagation in the as-spun alloy.     

NANOCRYSTALLINE STRUCTURE AND INITIAL PERMEABILITY OF ANNEALED Fe_（73．5）Cu_1W_3Si_（13．5）B_9 Alloy

ＮＡＮＯＣＲＹＳＴＡＬＬＩＮＥＳＴＲＵＣＴＵＲＥＡＮＤＩＮＩＴＩＡＬＰＥＲＭＥＡＢＩＬＩＴＹＯＦＡＮＮＥＡＬＥＤＦｅ_（７３．５）Ｃｕ_１Ｗ_３Ｓｉ_（１３．５）Ｂ_９ＡｌｌｏｙＺＨＡＮＧＸｉａｎｇｙｉ,ＺＨＡＮＧＪｉｎｇｗｕａｎｄＺＨＥＮＧＹａｎｇｚｅ?..     

Structural and Thermal Behavior of Fe-Cr-Mo-P-B-C-Si Amorphous and Nanocrystalline HVOF Coatings

The microstructure, thermal behavior, and mechanical properties of amorphous/nanocrystalline 70Fe-15Cr-4Mo-5P-4B-1C-1Si (wt.%) coatings produced by high velocity oxy fuel (HVOF) spraying of mechanically alloyed powders were investigated by x-ray diffractometry (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Thermal stability of samples was investigated using differential scanning calorimetry (DSC). The results show that by adjusting the HVOF parameters especially fuel/oxygen ratio and proper selection of powder composition, the desired microstructure with different amount of amorphous and nanocrystalline phases and therefore with different mechanical properties could be obtained.     

热处理对压铸镁合金化学镀层组织和性能的影响

采用化学镀方法在AZ91D压铸镁合金表面获得N i-P镀层,研究了不同热处理温度对镀层的组织和性能的影响。结果表明:镍层中P含量为6.22 wt%,镀层组织为非晶+少量纳米晶组织。随热处理温度升高原始镀层中的非晶组织中先形成镍纳米晶,然后纳米晶镍伴随晶化过程进行迅速长大,并在镍基体上析出N i12P5和N i3P相。镀层与基体的结合强度在350℃附近达最大结合强度为3.7 MPa,镀层硬度在400℃附近达最大值为825 HV;盐雾腐蚀实验表明镀层耐腐蚀性能良好,连续盐雾8 h未出现腐蚀斑点。经过不同的热处理,镀层的耐蚀性随着热处理温度的提高而下降。     

冷却速率对FeSiBCuNb合金条带磁学和耐腐蚀性能的影响

采用X射线衍射仪(XRD),振动样品磁强计(VSM),电化学工作站以及扫描电子显微镜(SEM)等试验仪器对辊速为14.65和43.96 m/s旋淬制备的Fe73.5Si13.5B9Cu1Nb3(C1和C2)合金条带进行了测试分析.XRD结果显示,低冷速下制备获得了非晶/纳米晶双相(C1)合金,高冷速制备的合金(C2)为...     

快速凝固粉末冶金Mg_(80)Cu_(10)Y_(10)合金的组织与力学性能

采用快速凝固粉末冶金技术制备热挤压Mg_(80)Cu_(10)Y_(10)合金棒材,研究了快速凝固Mg_(80)Cu_(10)Y_(10)合金薄带及热挤压后合金的相结构,并对热处理工艺对合金棒材组织结构及力学性能的影响进行了分析.研究表明,采用单辊快速凝固法在辊速为1800 r/min下制备的Mg_(80)Cu_(10)Y_(10)合金薄带为完全非晶态;在热挤压过程中Mg_(80)Cu_(10)Y_(10)合金中有Mg_2Cu和Mg晶体相析出,其显微硬度比薄带有所提高,这与合金中细小Mg_2Cu颗粒的弥散析出有关;在450 ℃保温4 h后的热挤压Mg_(80)Cu_(10)Y_(10)合金中没有新相析出;随着热处理温度的升高或保温时间的延长,由于Mg_2Cu颗粒出现重溶及聚集长大现象,使得热挤压Mg_(80)Cu_(10)Y_(10)合金的显微硬度表现出逐渐下降的变化趋势.     

Zr-基块体非晶合金近玻璃转变温度热处理后的组织与性能

选择在非晶合金的玻璃转变温度与晶化起始温度间的较低温度对Zr57Cu15.4Ni12.6Al10Nb5块体非晶合金进行了等温热处理，用X射线衍射、扫描电镜、显微硬度计与压缩试验，研究了等温热过程中非晶合金的组织结构变化及其对显微硬度与压缩性能的影响。结果表明，在近晶化温度下，一定时间的热处理会引起非晶合金的晶化。而在近玻璃转变温度下，较长时间的热处理也不会引起非晶合金出现明显的晶化和组织变化；但随着热处理时间的增长，合金的显微硬度有增大趋势，合金的压缩强度明显下降，断口形貌变化显著，断裂方式也逐渐由非晶态的断裂方式向晶态的断裂方式转变。     

Mg_(80)Cu_(15)Y_5合金的非晶形成能力及晶化行为

采用单辊快速凝同法制备出厚约40μm的Mg_(80)Cu_(15)Y_5非品合金薄带,利用XRD、DSC、TEM和HRTEM研究了非品合金的非品形成能力和晶化行为,分析了品化对合金组织结构与性能的影响.结果表明:Mg_(80)Cu_(15)Y_5合金的过冷液态温度区间△T_x和约化玻璃转变温度T_(rg)分别为55K和0.58,表明其具有较强的非晶形成能力;该合金在退火温度高于473 K后发牛明显晶化,从非品基体中析出 Mg_2Cu、Cu_2Y和Mg晶体相;随着退火温度的升高,合金的硬度呈现出先升高后降低的变化趋势,这与纳米品体相颗粒的弥散析出、重溶及粗化有关.     

Effects of chemical composition on nanocrystallization kinetics, microstructure and magnetic properties of finemet-type amorphous alloys

In this study, the kinetics of nanocrystallization of amorphous Fe_73.5Si_13.5B₉Nb₃Cu₁ (F1) and Fe₇₇Si₁₁B₉Nb_2.4Cu_0.6 (F2) alloys is investigated. The microstructure and magnetic properties of the nanocrystalline alloys are compared. The crystallization temperature of F2 alloy is shifted towards lower temperatures with respect to F1. Thus, the crystalline volume fraction and the crystalline grain size at specific annealing temperature for the F2 alloy are higher than for the F1 alloy, accounting for the higher coercive force of F2 alloy with respect to the one of F1 alloy. According to isoconversional methods, the activation energy for crystallization is variable as a function of transformed fraction because of the continuous changes in chemical composition during the transformation. Mean values of 350 and 290 kJ/mol are obtained for F1 and F2, respectively. Microstructural observations confirm that minor changes in chemical composition affect the kinetics and final microstructure of the nanocrystalline alloy, that determine the observed magnetic properties.