不同组分Cu-Cr、Cu-Mo机械合金化相演变特征

采用X射线衍射(XRD)仪与透射电镜(TEM)选区电子衍射(SAED)对不同组分Cu-Cr、Cu-Mo高能球磨粉末在机械合金化过程中的相演变特征进行了研究,Mo在Cu中以晶格固溶为主,通过机械合金化手段扩展Mo在Cu中的固溶度有限,随着Mo组分含量增加,Cu晶粒尺寸变小,Mo在Cu中固溶度增大,Cu-80%Mo球磨产物中有非晶相出现。Cr在Cu中的固溶以晶界亚互溶为主,球磨强度影响Cu-50%Cr(质量分数)合金化产物,较高球磨强度下生成Cu纳米晶与Cr的氧化物。     

机械合金化制备铜碳过饱和固溶体

采用机械合金化方法制备Cu-4wt%C过饱和固溶体,通过SEM和XRD分析研究了机械合金化中Cu-C复合粉末的形貌变化及碳在铜中的固溶度扩展问题.结果表明,机械合金化过程中Cu粉和C粉形成了层状复合粉末;随着球磨时间的增加,C的衍射峰逐渐消失,Cu的衍射峰逐渐宽化,并且位置发生偏移;球磨24h后,C原子固溶到Cu中,Cu的点阵常数达到0.3620nm,晶格膨胀了0.15%.     

机械合金化制备Cu-Cr合金时效强化特性的研究

采用机械合金化工艺制成Cu—Cr合金粉末,然后热压成形制备铜铬合金。采用XRD、TEM分析机械合金化过程中Cu-Cr合金粉末的显微组织和晶粒大小,测试了热压成形后Cu—Cr合金的力学和电学性能,探讨了材料的强化机制和热压温度对组织性能的影响。结果表明,Cu—Cr合金粉末可通过机械合金化获得过饱和固溶体,热压成形后,组织细小均匀,具有优良的综合性能。该合金经840℃热压并保温2h后,其强度达最大值,显微硬度为205．3HV,抗拉强度633．5MPa,电导率为80．4％IACS。合金中过饱和的Cr原子的作用是使合金沉淀强化。     

Cr对标准阴极铜组织与力学性能的影响

在大气环境下采用普通中频感应电炉熔炼制备了Cu-Cr合金,研究了铬对标准阴极铜组.织与力学性能的影响,Cr的加入量分别为0.30%、0.5 3%、0.76%和0.99%.结果表明,在本实验条件下,Cr可以有效地加入到Cu液中.铸态及固溶时效Cu-Cr合金中只存在α-Cu相与Cr相.铸态时部分Cr溶于基体中,部分Cr以第二相形式存在;固溶时效后基体中可分解析出更多弥散分布的Cr相.Cr元素对纯铜有强化作用,合金的铸态和热处理态试样的拉伸强度及硬度均随Cr元素加入量的增大而增加.固溶时效热处理能有效提高铸态Cu-Cr合金的力学性能.     

若干简单金属与类金属在Ag中固溶度亚稳扩展的研究

用点阵参数法研究了在熔体淬火条件下若干简单金属与类金属在Ag中固溶度的亚稳扩展。发现与Ag发生一系列包晶反应的二元合金的固溶度扩展符合电子浓度规律,并结合相图特征讨论了包晶系固溶度扩展的规律。简单共晶合金的固溶度扩展并不满足电子浓度规律,用Miedema理论解释了Si在Ag中固溶度低的原因。     

METASTABLE EXTENSION OF SOLID SOLUBILITY OF CERTAIN SIMPLE METALS OR METALLOIDS IN Ag

用点阵参数法研究了在熔体淬火条件下若干简单金属与类金属在Ag中固溶度的亚稳扩展。发现与Ag发生一系列包晶反应的二元合金的固溶度扩展符合电子浓度规律,并结合相图特征讨论了包晶系固溶度扩展的规律。简单共晶合金的固溶度扩展并不满足电子浓度规律,用Miedema理论解释了Si在Ag中固溶度低的原因。     

不同固溶处理对Cu-Cr系合金组织和性能的影响

热处理工艺调控是提升Cu-Cr系合金性能的有效方法。Cu-Cr系合金的固溶工艺大多选择温度较低的Cu-Cr两相区进行,导致Cr相固溶程度不完全,抑制后续析出强化效果。本研究提出采用高温单相区固溶工艺改善析出强化效果,主要研究不同固溶工艺(Cu-Cr两相区(950℃,4 h)和Cu单相区(1050℃,6h))对Cu-Cr系合金组织和性能的影响。采用电子探针(EPMA)对两种固溶工艺后的元素分布进行表征,并对峰值时效态合金的微观结构采用XRD和TEM进行表征分析。结果表明：与两相区固溶相比,单相区固溶后铸态Cr相充分固溶,时效过程中更多纳米Cr相弥散析出;合金力学性能相比两相区固溶后峰值时效态有较大提升,其中屈服强度提升29.3%,抗拉强度提升25.6%,而导电率并未明显下降。强度理论计算结果表明,析出强化所贡献的屈服强度增量为323.4 MPa,贡献56.9%,析出强化是本研究中最主要的强化机制。     

低温球磨纳米晶Al-Zn-Mg-CU合金组织的演变

利用液氮低温球磨技术制备了纳米晶Al-Zn—Mg—Cu合金粉体,分析了材料在球磨过程中微观组织变化．结果表明,气雾化Al—Zn—Mg—Cu合金粉体随着球磨过程的进行晶粒尺寸逐渐减小,球磨15h后晶粒尺寸约为35nm;MgZn2相逐步分解,并最终过饱和固溶于α—Al中．制备的纳米晶Al—Zn—Mg—Cu合金粉体低于709K（0．77Tm,Tm为熔点）加热时,晶粒长大速度缓慢;709K加热1h晶粒尺寸仅为71nm．研究表明,液氮低温球磨过程中形成的Al2O3颗粒对晶粒的钉扎有效地提高了纳米晶Al-Zn—Mg—Cu合金粉体的热稳定性．     

机械合金化法制备不同Cr含量的W-Cr纳米合金粉末

采用机械合金化法制备Cr含量为8%、12.5%、20%（质量分数）的纳米W-Cr合金粉,对不同球磨时间粉末进行X射线衍射分析,以确定物相、晶粒尺寸及微应变,并采用扫描电子显微镜观察粉末形貌及粒度的变化。结果表明,采用机械合金化法可以制备不同Cr含量的纳米W-Cr合金粉。随着Cr含量的增加,制备纳米W-Cr合金粉所需球磨时间越长,其中W-8%Cr、W-12.5%Cr和W-20%Cr粉末的最佳球磨时间分别为72、84和96 h,晶粒尺寸小于30 nm。随着球磨时间的增加,晶粒尺寸不断减小,微应变逐渐增加,使常温下Cr在W中的固溶度增加,形成W的过饱和固溶体。Cr含量不同的W-Cr粉末完全合金化均经过4个阶段。     

爆炸喷涂Al-Cu-Cr准晶涂层的组织及硬度研究

为了研究热喷涂工艺对爆炸喷涂Al-Cu-Cr准晶涂层组织和硬度的影响规律,采用三种爆炸喷涂工艺参数在Q235A低碳钢基体上制备涂层,借助XRD、SEM和OM等技术手段对粉末和涂层的组织结构进行分析,并检测涂层横截面的孔隙率和显微硬度.结果表明,用于喷涂的Al65Cu20Cr15准晶粉末中含有二十面体准晶相i-Al65Cu24Cr11和极少量具有单斜结构的晶体相θ-Al13Cr2(即Al83Cu4Cr13);而爆炸喷涂涂层中除i和θ两相外,生成了新相--体心立方结构的α-Al69Cu18Cr13(准晶i的晶体类似相)和Al203相.涂层呈典型层状结构,其它条件不变的情况下,涂层中各晶体相与准晶相i最强峰衍射强度的比值α/i、θ/i和Al2O3/i随爆炸喷涂工作气体流速的成比例提高而增加,同时涂层截面的孔隙率下降而显微硬度HV0.1升高.     

The pitting corrosion of sputtered Fe base alloy films

Predominantly single phase Fe base alloy films were prepared by a DC sputtering method. The compositions of the alloy films, as determined by Auger electron spectroscopy (AES) were Fe-7 at% Cr and Fe-18 at% Cr, Fe-11 at% W and Fe-19 at% W, Fe-9, −13 and −27 at% Ta. The pitting potential of the sputtered alloys determined in chloride solutions was found to be strongly dependent on the nature and the concentration of the alloying element. The pitting potential of sputtered Fe-18 at% Cr and Fe-27 at% Ta alloy films were approximately 0.9 V higher than that of bulk Fe and 0.6 V higher than that of Fe-19 at% W alloy film. A very good correlation was found between the pitting potential of Fe alloy films and the solubility of an alloying element oxide in acidic solutions with a pH corresponding to that within the stable pits of pure Fe (pH = 2). The pitting potential of the Fe alloy was found to increase with a decrease in the solubility of the alloying element oxide in acidic solutions. The pitting potentials of the sputtered Fe-7 at% Cr and Fe-18 at% Cr alloy films were were significantly higher than those of the bulk materials with the same composition. The higher pitting potentials of these alloy films are tentatively attributed to the presence of very fine particles of the oxide phase that are homogeneously distributed in the sputtered alloys.     

磁控溅射Cu-Cr合金薄膜与Sn-Ag-Cu焊料在时效处理时的界面反应

采用磁控溅射的方式沉积不同Cr含量的Cu-Cr合金薄膜,通过与Sn-Ag-Cu(SAC)焊料在240 ℃下回焊形成焊点结构,然后将试样置于180 ℃下进行真空时效处理。研究Cu-Cr合金作为凸点下金属化(UBM)层时与SAC形成焊点的焊接可靠性。使用配备能量色散X射线光谱仪的场发射扫描电镜和多功能推力测试仪等分析界面金属间化合物(IMC)的形貌及焊点的剪切强度。结果表明,SAC/Cu-Cr焊点结构在回焊后形成了不同于传统的SAC/Cu焊点扇贝状IMC的针状IMC。在时效处理后,Cr在晶界处的偏析形成了富铬层,其作为扩散阻挡层阻碍Cu扩散到IMC中,使得Cu₃Sn和柯肯达尔空洞的生长受到抑制。剪切强度测试结果表明,回焊后SAC/Cu-Cr试样比SAC/Cu试样具有更高的剪切强度。Cr靶电流为1.5 A的Cu-Cr合金UBM层形成的焊点结构具有较小的IMC厚度,且拥有最高的焊点剪切强度。证实了Cu-Cr 合金UBM层有利于提高焊接可靠性。     

Cu-Cr复合材料的燃烧合成-熔铸过程的研究

提出了制备大功率真空断路器中Cu-Cr触头复合材料的燃烧合成-熔铸工艺.通过对CuO-Cr2O3-Al反应体系的热力学计算,分析了该体系发生燃烧合成反应并形成Cu-Cr合金熔体的可行性,研究了熔体的凝固过程和最终获得材料的显微组织.结果表明,以廉价的CuO、Cr2O3、和Al粉为原料,利用燃烧合成-熔铸工艺可以制备晶粒细小的Cu-Cr复合材料.     

Dechromisation of Cu-Cr alloy in acid solutions containing Cl~-

1　INTRODUCTIONItisveryimportanttoexploitanewkindofCualloyswithexcellentanti corrosion performancebe causeCualloy ,asakindofanti corrosionmaterialsappliedforalongtime ,oftenundertakesleakageandseriouscorrosionintheearlystageduringitsser vice[1] .Cu Cralloyhashighstrengthandexcellentelectricconductivityandheatconductivity ,anditisappliedwidelytopreparefunctionaldevicesinhighstrength ,highconductivityfields .Althoughmanyattentionwas paidtotheCu Cralloyandalargenumberofworkshadbeendone[2 12…     

Effects of extrusion on chromium precipitation in Cu-Cr alloy

1　INTRODUCTIONChromiummaycrystallizeasashortbarorden driteduringsolidificationofCu Cralloy[13] .AllkindsofCrparticlesmaydissolveintocoppermatrixduringsolutiontreatmentat 980℃ .Duringthesub sequentaging ,thechromiumdissolvedincopperma trixwillprecipitate[4 6 ] .Theprecipitatedchromiumparticleshavegreateffectsonmechanicalandelectri calpropertiesofCu Cralloyaccordingtotheirsize ,shapeanddistribution[79] .Someworksfocusedoneffectofalloyingadditionsonthesizeofchromiumparticleandpropertyof…     

Microstructures and Thermal Properties of Cold-Sprayed Cu-Cr Composite Coatings

Copper-based composites for thermal conductive components were prepared via the cold spray process, and the deposition efficiency and adhesion morphology of feedstock powders on Cu substrate were evaluated. Cu-based composites were fabricated using Cu-Cr mixed powders with their mixture ratio of 20, 35, 50, and 65 mass% Cr onto oxygen-free copper substrate with N₂ carrier gas. Cu-Cr composite coatings were investigated for their Cr content ratio, microstructures, and thermal conductivity. The Cr content ratio in the coating was approximately 50-60% of feedstock mixture ratio due to the low formability of the hard particles. Transmission electron microscopy characterizations revealed that an oxygen-rich layer exists at the Cr particle/Cu substrate interface, which contributes to the deposition of the Cr particles. After the heat treatment at 1093 K, the coatings showed denser cross-sectional structures than those before the heat treatment, and the thermal conductivity was improved as a result of the recrystallization of Cu matrix.     

FORMATION LAW OF PHASES IN ULTRAFINE POWDERS OF Al-Cu ALLOY PREPARED BY GAS EVAPORATION PROCESS

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Effect of temperature on mechanical alloying of Cu-Zn and Cu-Cr system

Cu-Zn and Cu-Cr powders were milled with an attritor mill at room temperature, −10, −20 and −30 °C, respectively. Phase transformation and morphology evolution of the alloyed powder were investigated by X-ray diffractometry(XRD), X-ray photoelectron spectroscopy(XPS) and scanning electron microscopy(SEM). The results show that lowering temperature can delay mechanical alloying(MA) process of Cu-Zn system with negative mixing enthalpy, and promote MA process of Cu-Cr system with positive mixing enthalpy. As for Cu-Cr and Cu-Zn powders milled at −10 °C, lamellar structures are firstly formed, while fewer lamellar particles can be found when the powder is milled at −20 °C. When the alloyed powder is annealed at 1 000 °C, Cu(Cr) solid solution is decomposed and Cr precipitates from Cu matrix, whereas Cu(Zn) solid solution keeps stable.