高强度Cu-Ni-(Al)-Si合金的组织和性能

通过光学显微镜、维氏硬度计、双臂电桥、扫描电子显微镜、透射电子显微镜等测试手段对Cu-5.2Ni-1.2Si和Cu-5.2Ni-1.5Al-1.2Si合金的组织结构和性能进行了表征与测试。结果表明:2种合金的铸态组织均为发达的树枝晶组织,包括白亮的枝晶区、非平衡凝固相粒子及中间过渡区。其中枝晶为富Cu区,凝固相为富Ni和Si区,Al元素则比较均匀地分布在铸态组织中。峰值时效后,Cu-5.2Ni-1.5Al-1.2Si合金具有比Cu-5.2Ni-1.2Si合金更高的硬度。Al元素不但促进了Ni2Si的沉淀析出,还形成了Ni3Al沉淀相,从而大大提高合金强度。2种合金的时效早期均出现了有序化,峰时效时主要为沉淀析出强化,合金具有较好的抗过时效能力。     

Microstructure and properties of Cu–2.8Ni–0.6Si alloy

The phase transformation behavior and heat treatment response of Cu-2.8Ni-0.6Si (wt%) alloy subjected to different heat treatments were studied by X-ray diffraction, transmission electron microscopy observation, and measurement of hardness and electrical conductivity. The variation of hardness and electrical conductivity of the alloy was measured as a function of aging time. On aging at the temperature below TR (500-550°C) in Cu-2.8Ni-0.6Si alloy, the transformation undergoes spinodal decomposition, DO22 ordering, and d-Ni2Si phase. On aging at the temperature above TR (500-550 °C), the transformation products were precipitations of d-Ni2Si. The free energy versus composition curves were employed to explain the microstructure observations.     

Effects of Ti addition and heat treatments on mechanical and electrical properties of Cu-Ni-Si alloys

The mechanical and electrical properties of Cu-5.98Ni-1.43Si and Cu-5.98Ni-1.29Si-0.24Ti alloys under heat treatment at 400 and 500 °C after hot- and cold-rolling were investigated, and a microstructural analysis using transmission electron microscopy was performed. Cu-5.98Ni-1.29Si-0.24Ti alloy displayed the combined Vickers hardness/electrical conductivity value of 315.9 Hv/57.1%IACS. This was attributed to a decrease of the solution solubility of Ni and Si in the Cu matrix by the formation of smaller and denser δ-Ni₂Si precipitates. Meanwhile, the alloyed Ti was detected in the coarse Ni-Si-Ti phase particles, along with other large Ni-Si phase particles, in Cu-5.98Ni-1.29Si-0.24Ti.     

NiTi40合金微观组织结构的电子显微学分析

采用扫描电子显微分析(SEM)、电子背散射衍射分析(EBSD)、透射电子显微分析(TEM)、高分辨电子显微分析(HRTEM)、高角度环形暗场-扫描透射(HAADF-STEM)等技术手段,对NiTi40(60%Ni+40%Ti,质量分数)合金淬火态样品的微观组织结构进行分析。结果表明:NiTi40合金在950℃、150 min固溶水冷和1050℃、150 min固溶水冷的硬度值相近,为60~61 HRC,但微观组织结构有显著的区别。经950℃固溶水冷后,合金中的粗大第二相主要为NiTi2和Ni3Ti相,还有少量和NiTi2相互伴生的TiC相;经1050℃固溶水冷后,合金中的Ni3Ti相接近完全回溶的,粗大第二相主要为相互伴生的NiTi2及Ti C相。随着固溶温度的升高,合金的晶粒尺寸明显增大,合金晶界处的小晶粒在1050℃固溶时基本消失。经950℃固溶处理,晶内析出相主要为10~20 nm的Ni4Ti3相;经1050℃固溶处理,晶内析出相主要为几十至几百纳米的Ni4Ti3相。     

PRECIPITATION BEHAVIOUR AND HARDENING OF B2-ORDERED Ni(Al, Ta)

1.IntroductionIntermetalliccompoundsbasedonNiAIwithlowdensities(<5.9g/cm')andhighmeltingtemperatures(>1900K)areattractiveforpotentialhightemperaturestructuralapplications.However,beforethesecompoundscanbeexploitedforthispurposetheirlowductilityandinadequatehightemperaturestrengthmustbeimprovedinordertocompetewithealstingalloyonastreng'thtoweightbasis.VariousinvestigationsofthemechanicalpropertiesoftheBZ-orderedNiAIhavebeenreportedtl--7];includingworkonternaryalloys,Ni-ALX,whereXincludesr…     

Identifying the glass transitions for an Al85Ni5Y6Fe2Co2 metallic glass using a temperature modulated scanning calorimetry

Al85Ni5Y6Fe2Co2金属玻璃在240 ℃等温退火15 min后, 示差扫描量热仪(DSC)曲线出现2个吸热台阶, 一般认为该现象由2个玻璃转变引起, 但温度调制示差扫描量热仪(TMDSC)结果表明2个吸热台阶并非对应2个玻璃转变. 透射电子显微镜Z衬度相及EDS扫描曾观测到300 ℃非等温退火的样品发生非晶相分离现象, 但TMDSC在该样品中也仅观测到1个玻璃转变.     

Metastable phase transitions in Mo-Si and V-Si systems activated by high energy ball milling

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Al-0.66Mg-0.85Si合金均匀化过程中的组织演变(英文)

采用金相显微镜、扫描电子显微镜、透射电子显微镜和差示扫描量热法研究Al-0.66Mg-0.85Si合金在均匀化过程中的组织演变。合金铸态组织呈典型的枝晶形貌,存在α(Al)、Al15(FeMn)3Si2、Mg2Si,、Q(Al1.9CuMg4.1Si3.3)和Si相。铸态组织中存在2种不同晶体结构的Mg2Si相,一种是在铸造过程中形成的,另一种是在铸造完成后的空冷过程中形成的。经过545°C、20 h均匀化处理之后,组织中的Q、Mg2Si和Si相已完全溶入基体,残留的第二相主要是Al15(FeMn)3Si2相。Al15(FeMn)3Si2相的尺寸减小、球化并且在晶界上断续分布。在铸态和均匀化热处理状态中,均未发现含Zn相。     

高性能Al-Si-Cu-Ni-Mg活塞合金的相分析

采用高倍视频金相显徽镜（HRVM）和电子探针（EPMA）微区分析技术,观察了高性能Al-Si-Cu-Ni-Mg活塞合金的显微组织形貌,确认了合金中存在的构成相Mg2Si、Al3Ni、W相以及（CuNi）2Al3相。着重观察分析W相和Mg2SiN在热处理过程中的形态演变,发现多元共晶体中的W相固溶后由无序网格状呈现出典型的骨架状或者密堆状,Mg2Si相固溶处理后主要以固溶强化相融入到基体中。     

激光熔覆Ni2Si／Ni3Si2金属硅化物合金涂层显微组织与耐蚀性

以Ni76Si24（质量百分数）合金粉末为原料，利用激光熔覆技术在A3钢表面制得了组织由条件Ni2Si初生相及少量Ni2Si/Ni3Si2共晶组成的新型金属硅化物合金涂层，分析涂层显微组织并测定其在0．5mol/1 H2SO4水溶液及不同浓度NaCl水溶液中的阳极极化曲线，结果表明激光熔覆Ni2Si/Ni3Si2金属硅化物合金涂层表面平整，组织细小，与基体为完全冶金结合，同时由于涂层的组织组成相Ni3Si2本身均具有极好的耐蚀性并具有快速凝固细小均匀的显微组织，该激光熔覆Ni2Si/Ni3Si2金属硅化物合金涂层在0．5mol/l H2SO4及3．5％NaCl水溶液中均具有优良的耐蚀性能。     

Microstructural characteristics and paint-bake response of Al-Mg-Si-Cu alloy

The microstructural characteristics and paint-bake response of 6022 alloy with 0.3% Cu （mass fraction） were studied using optical microscope, scanning electron microscope（SEM）, transmission electron microscope（TEM） and tensile tester. The results indicate that the phase constituents in the as-cast microstructure are Mg2Si, Si, Al5Cu2Mg8Si6, Al5FeSi, α-Al（MnCrFe）Si and CuAl2. During the following homogenization, CuAl2, Al5Cu2Mg8Si6 and Mg2Si phases are almost completely dissolved, and Al5FeSi transforms to α-Al（MnCrFe）Si particles. After rolling, the phase constituents in the alloy change less except the precipitation of Mg2Si particles, and the precipitation behavior of Mg2Si strongly depends on the thermomechanical conditions. Cu addition significantly increases the paint-bake response of 6022 alloy by facilitating the formation of β＂ phase. Therefore, the tensile strength of 6022 alloy with 0.3% Cu is higher than that of 6022 alloy without Cu after paint-bake cycle.     

Zr-Ti-Cu-Ni-Be大块非晶合金等温晶化过程相分离研究

利用差示扫描量热法(DSC)和透射电镜(TEM)对Zr41.2Ti13.8Cu12.5Ni10Be22.5(at％)大块非晶合金的等温晶化过程和析出相进行了研究。结果表明，大块非晶合金在等温晶化过程中表现出多阶段相析出行为，并且在不同的晶化阶段，析出相也有所不同。在第1个晶化阶段，析出相主要是体心四方(b.c．t)结构的Zr2Cu相；而在晶化的第2个阶段，晶化相主要为简单六方结构的ZrBe2相。从一定程度上证实了Zr41.2Ti13.8Cu12.5Ni10Be22.5大块非晶合金在发生晶化时会形成富Zr区和富Be区，即有相分离的趋势。XRD测试的结果也证实了非晶合金在发生完全晶化时，主要的晶化产物为Zr2Cu和ZrBe2相。     

Effect of Ti addition on tensile properties of Cu-Ni-Si alloys

This study examines how varying Ni and Si contents and the addition of Ti affect the tensile behavior of Cu-Ni-Si alloys with different aging conditions. Cu-3Ni-0.7Si and Cu-6Ni-1.4Si alloys, both with and without the addition of Ti, were prepared by solution-heat treatment at 950 °C for 2 h, then aged at 500 °C for 1/ 6 h, 1/3 h, 1/2 h, 1 h, 3 h and 6 h, before tensile tests were conducted. Doubling the Ni and Si contents in Cu-Ni-Si alloys greatly increased the tensile strength and grain refinement, while marginally reducing the tensile elongation. Meanwhile, adding Ti to Cu-Ni-Si alloys reduced the grain size and greatly increased the tensile elongation. The aging response was also significantly accelerated by the addition of Ti. However, the expected improvement in tensile strength was not obtained by adding Ti, addition due to the agglomeration of coarse Ni₂Si precipitates and the accelerated lamellar structure formation. Finally, we discuss the microstructural changes that result from variations in aging time, different Ni and Si contents and the addition of Ti on Cu-Ni-Si alloys based on detailed optical, scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographic observations and SEM fractographic analysis.     

Ni-Ti-O纳米片/泡沫镍复合电极的显微结构及其电化学性能

采用了水热合成和热扩渗结合的方法在三维多孔泡沫镍支架上制备了Ni-Ti-O纳米片层。通过扫描电镜（SEM）、X射线衍射（XRD）、透射电镜（TEM）、高分辨透射电镜（HRTEM）对泡沫镍支架上NiO和Ni-Ti-O纳米结构的微观形貌及物相进行了观察表征和物相分析。用循环伏安法和充放电性能测试探究了复合电极对甲醇的催化氧化性能及其电容性能。结果表明：泡沫镍上生长的Ni-Ti-O纳米片物相组成为NiO和TiO,并且为多晶形态;Ti的渗入会使得NiO纳米片中形成氧空位,并和Ni产生协同作用,使得Ni-Ti-O纳米片/泡沫镍电极的对甲醇氧化的电催化性能优于Ni(OH)2/泡沫镍和NiO/泡沫镍电极;泡沫镍和钛粉质量比（RNi/Ti）为1:24,在电流密度为5 mA?cm-2时,Ni-Ti-O电极的面积比电容值为 2.15 F?cm-2,是纳米Ni(OH)2/泡沫镍电极的3.2倍（0.67 F?cm-2）。     

Cu-9.5Ni-2.3Sn-0.5Si合金的固溶处理工艺与组织性能研究

采用金相显微镜、扫描电镜、EDAX能谱仪、X射线衍射仪、SIGMASCOPE SMP10型导电仪、维氏硬度计等,研究了热处理工艺对Cu-9.5Ni-2.3Sn-0.5Si合金组织和性能的影响。结果表明:Cu-9.5Ni-2.3Sn-0.5Si合金晶粒尺寸随固溶温度升高而长大;随着固溶温度的升高或固溶时间的延长,电导率先降后升,而硬度则下降。此外,合金经850℃×2 h固溶处理后,形成了Ni2Si、Ni31Si12相并占据了γ-(Cu,Ni)3Sn相的形核位置,此时电导率为12.0%IACS,硬度可达152 HV。     

Amorphization of Fe38Ni30Si16B14V2 surface layers by laser cladding

Fe38Ni30Si16B14V2 amorphous composite coatings were fabricated by laser cladding on AISI 1045 steel in order to increase the wear resistance. The phase and microstructure of the coatings were analyzed by X-ray diffractometry and transmission electron microscopy. The wear properties of the coatings were also investigated by means of sliding wear test. The results show that the coating consists of amorphous phase in majority and nanocrystalline phase in minority. The amorphous coatings can be obtained while the scanning speed is 3 500 mm/min and the laser power is 4.8 kW. With increase of the laser power, the amorphous phase in the coating increases when it is lower than 4.8 kW. A gradient distribution of the microhardness ranges from Hv0.2 1 208 to Hv0.2 891 in the coating from top surface of the coating to the substrate. The amorphous coating is found to possess better property of wear than AISI 1045 steel substrate.     

镍基合金TLP扩散焊接头中二元共晶沉淀相Ni-M(B、Si、Zr和Hf)的性能

采用基于密度泛函理论的第一性原理平面波赝势计算方法,计算了Ni-M(B、Si、Zr和Hf)二元共晶沉淀相(Ni2B、Ni3B、Ni3B2、Ni23B6、Ni3Si、Ni5Zr和Ni5Hf)的相稳定性、弹性常数、硬度及相应的电子结构.相稳定性计算结果表明,二元共晶沉淀相结构稳定性变化趋势由高到低的顺序为Ni3Si、Ni5...     

Microstructure and mechanical properties of laser melting deposited Ti2Ni3Si/NiTi Laves alloys

Two Ti2Ni3Si/NiTi Laves phase alloys with chemical compositions ofNi-39Ti-11Si and Ni-42Ti-8Si （%, mole fraction, the same below）, respectively, were fabricated by the laser melting deposition manufacturing process, aiming at studying the effect of Ti, Si contents on microstructure and mechanical properties of the alloys. The Ni-39Ti-llSi alloy consisting of Ti2Ni3Si primary dendrites and Ti2Ni3Si/NiTi eutectic matrix is a conventional hypereutectic Laves phase alloy while the Ni-42Ti-8Si alloy being made up of NiTi primary dendrites uniformly distributed in Ti2Ni3Si/NiTi eutectic is a new hypoeutectic alloy. Mechanical properties of the alloys were investigated by nano-indentation test. The results show that the decrease of Si and the increase of Ti contents change the microstructures of the alloys from hypereutectic to hypoeutectic, which influences the mechanical properties of the alloys remarkably. Corrosion behaviors of the alloys were also evaluated by potentiodynamic anodic polarization curves.     

Transformation of Mg2Si during TEM foil preparation

Decomposition of Mg₂Si particles was observed as foils of aluminum alloys were jet polished for transmission electron microscopy (TEM). Mg₂Si in contact with a HNO₃-methanol solution is converted to an amorphous SiO(H) phase. The amorphous phase remains as an artifact in the foil because the volume change associated with the transformation is small. Primary silicon particles were not altered during jet thinning.     

In situ observation of Cu segregation and phase nucleation at a solid–liquid interface in an Al alloy

This paper presents a systematic study comparing experimental in situ transmission electron microscopy observation of microstructural and compositional evolution with complementary thermodynamic calculations, to better understand the redistribution of solute elements and the nucleation behavior of different phases in a commercial Al-alloy powder (AA390). The results show that Cu segregation to the solid Si–liquid Al interface, as well as the significant undercooling achieved in the liquid under non-equilibrium conditions because the Al phase cannot nucleate homogeneously, play a important roles in nucleating Al₂Cu at the interface prior to the Mg₂Si phase in the alloy. Although Cu segregation can occur at various locations along the interface, the Al₂Cu phase appears to preferentially nucleate at a high-index Si–liquid interface as opposed to a low-index one. The Cu concentration during segregation remains essentially constant with time, indicating that the observed segregation behavior is a thermodynamic and not a kinetic phenomenon. These in situ observations and complementary thermodynamic calculations substantially enhance our understanding of potential crystal nucleation and growth processes.