高温变形FeAL金属间化合物中的位错蜷线

高温变形ＦｅＡＬ金属间化合物中的位错蜷线洪建明，赵晓宁，刘毅，郦定强，林栋梁，陈世朴（南京大学现代分析中心，南京２１０００８）（上海交通大学材料科学系）具有Ｂ＿２结构的金属间化合物ＦｅＡｌ，由于具有良好的抗氧化性能、高温性能、比铁基和镍基合金较低的密...

Effect of Mo and ZrO_(2)nanoparticles addition on interfacial properties and shear strength of Sn58Bi/Cu solder joint

The influence of Mo and ZrO_(2)nanoparticles addition on the interfacial properties and shear strength of Sn58Bi solder joint was investigated.The interfacial microstructures of Sn58Bi/Cu,Sn58Bi+Mo/Cu and Sn58Bi+ZrO_(2)/Cu solder joints were analysed using a scanning electron microscope(SEM)coupled with energy dispersive X-ray(EDX)and the X-ray diffraction(XRD).Intermetallic compounds(IMCs)of MoSn_(2)are detected in the Sn58Bi+Mo/Cu solder joint,while SnZr,Zr_(5)Sn_(3),ZrCu and ZrSn_(2)are detected in Sn58Bi+ZrO_(2)/Cu solder joint.IMC layers for both composite solders comprise of Cu_(6)Sn_(5) and Cu_(3)Sn.The SEM images of these layers were used to measure the IMC layer’s thickness.The average IMC layer’s thickness is 1.4431μm for Sn58Bi+Mo/Cu and 0.9112μm for Sn58Bi+ZrO_(2)/Cu solder joints.Shear strength of the solder joints was investigated via the single shear lap test method.The average maximum load and shear stress of the Sn58Bi+Mo/Cu and Sn58Bi+ZrO_(2)/Cu solder joints are increased by 33%and 69%,respectively,as compared to those of the Sn58Bi/Cu solder joint.By comparing both composite solder joints,the latter prevails better as adding smaller sized ZrO_(2)nanoparticles improves the interfacial properties granting a stronger solder joint.

GT30光板的缺陷检测方法

目前PCB被广泛地应用于各种电子零部件中。PCB在生产过程中可能会因为各种因素而导致出现缺陷,最终影响产品的质量。因此,及时、有效地检测出PCB的质量缺陷就成了一个急需解决的问题。为此,以GT30光板为检测对象,参考IPC-TM-6502.1.1F:2015和GB/T 16594-2018标准要求,对样品进行了固封、研磨、抛光和蚀刻等处理,使用金相显微镜进行切片检查、不同位置的铜厚(PCB侧焊盘)测量和IMC检测。通过对检测结果的数据和图像进行分析,可以得出该方法能够精准有效地检测出GT30光板中的缺陷,且对厚度的检测精度能达到0.01μm,具有一定的参考价值。

β-~6LiAl晶体中氚释放行为的研究

β-~6LiAl金属间合物晶体用Tammann方法生长,X射线劳厄法分析。在中子照射过的;β-~6LiAl中,氚的示踪扩散系数用放射性色谱法测定。指出氚扩散系数的Arrhenius对数直线在700K附近的弯曲可能与晶体缺陷结构的变化有关。

Microstructure and wear resistance of laser clad TiB-TiC/TiNi-Ti_2Ni intermetallic coating on titanium alloy

A wear resistant TiB-TiC reinforced TiNi-Ti2Ni intermetallic matrix composite coating（TiB-TiC/TiNi-Ti2Ni） was prepared on Ti-6.5Al-2Zr-1Mo-1V titanium alloy by the laser cladding process using Ti＋Ni＋B4C powder blends as the precursor materials.Microstructure and worn surface morphologies of the coating were characterized by optical microscopy（OM）,scan electron microscopy（SEM）,X-ray diffraction（XRD）,energy dispersive X-ray analysis（EDS） and atomic force microscopy（AFM）.Wear resistance of the coating was evaluated under dry sliding wear test condition at room temperature.The results indicate that the laser clad coating has a unique microstructure composed of flower-like TiB-TiC eutectic ceramics uniformly distributed in the TiNi-Ti2Ni dual-phase intermetallic matrix.The coating exhibits an excellent wear resistance because of combined action of hard TiB-TiC eutectic ceramic reinforcements and ductile TiNi-Ti2Ni dual-phase intermetallic matrix.

Effect of Fe and Mo additions on microstructure and mechanical properties of TiAl intermetallics

The ductility of TiAl intermetallics can be improved through stabilizing the ductile β phase.New β-stabilized Ti-45Al-xFe-yMo（x,y=1,2,3,4） alloys were designed through adding the β stabilizing elements Fe and Mo.The microstructural evolution and deformation behavior of the Ti-45Al-xFe-yMo alloys were investigated.The results show that the amount of β（B2） phase is increased with the increase of alloying elements.Mo shows a higher capability for stabilizing the β phase than Fe.In the optimized Ti-45Al-3Fe-2Mo alloy,the grains are significantly refined to about 12 μm,and this alloy shows a very good hot ductility at the elevated temperature.

Multilayered Ti-Al intermetallic sheets fabricated by cold rolling and annealing of titanium and aluminum foils

Multilayered Ti-Al based intermetallic sheets were fabricated by sintering alternately layered titanium and aluminum foils.The microstructure and phase formation of the obtained sheets under different sintering conditions were evaluated by various techniques.The results reveal that when the sintering temperature is above the melting point of aluminum,the self-propagating high-temperature synthesis reaction occurs between Ti and Al,and forms various phases of Ti-based solid solutions including α-Ti Ti3Al,TiAl,TiAl2 and α-Ti including TiAl3,etc.When the sintering time increased,Ti-based solid solution,TiAl2 and TiAl3 disappeared gradually,and the sheet containing Ti3Al and TiAl phases in a multilayered structure formed finally.A lot of voids were also observed in the sintered structures,which were caused by the melting Al,Kirkendall effect and the difference of molar volumes between reactants and products.The voids were eliminated and a dense sample was obtained by the following hot press.

Effect of Si on growth kinetics of intermetallic compounds during reaction between solid iron and molten aluminum

The effect of Si on the growth kinetics of intermetallic compounds during the reaction of solid iron and molten aluminum was investigated with a scanning electron microscope coupled with an energy dispersive X-ray spectroscope, and hot-dip aluminized experiments. The results show that the intermetallic layer is composed of major Fe2Al5 and minor FeAl3. The Al-Fe-Si ternary phase, rl/rg, is formed in the Fe2Al5 layer. The tongue-like morphology of the Fe2Als layer becomes less distinct and disappears finally as the content of Si in aluminum bath increases. Si in the bath improves the prohibiting ability to the growth of Fe2Als and FeAl3. When the contents of Si are 0, 0.5%, 1.0%, 1.5%, 2.0% and 3.0%, the activation energies of Fe2Al5 are evaluated to be 207, 186, 169, 168, 167 and 172 kJ/mol, respectively. The reduction of the activation energy might result from the lattice distortion caused by Si atom penetrating into the Fe2Al5 phase. When Si atom occupies the vacancy site, it blocks easy diffusion path and results in the disappearance of tongue-like morphology.

Effects of Fe-Al intermetallic compounds on interfacial bonding of clad materials

The growth of intermetallic compounds at the interface between solid Al and Fe and the effects of intermetallic compound layers on the interfacial bonding of clad materials were investigated. The results showed that the interface between the solid Fe and Al formed by heat-treatment consisted of Fe2Al5 and FeAl3 intermetallic compound layers, which deteriorated the interfacial bonding strength. Fractures occurred in the intermetallic compound layer during the shear testing. The location of the fracture depended on the defects of microcracks or voids in the intermetallic compound layers. The microcracks in the intermetallic compound layer were caused by the mismatch of thermal expansion coefficients of materials during cooling, and the voids were consistent with the Kirkendall effect. The work will lay an important foundation for welding and joining of aluminum and steel, especially for fabrication of Al-Fe clad materials.

Effect of stannum addition on microstructure of as-cast and as-extruded Mg-5Li alloys

Mg-5Li-xSn （x=0.15, 0.25 and 0.65, mass fraction） alloys were prepared. The microstructures of these alloys were investigated through optical microscope （OM）, scanning electron microscope （SEM）, X-ray diffractometer （XRD） and energy dispersive spectrometer （EDS）. The results indicate that Sn additions produce a strong grain refinement effect on Mg-5Li alloy. The mean grain size of as-cast Mg-Li alloys with Sn is reduced remarkably from 556 μm to 345 μm, and that of the as-extruded alloys is reduced from 33 μm to 23 μm when the Sn content increases from 0.15% to 0.65%. The near net-like Mg2Sn phase in the as-cast alloys is verified at the grain boundaries. After extrusion, the granular Mg2Sn phase mainly exists inside the grains and thus can act as nucleation sites of α-Mg grains during the dynamic recrystallization and make the microstructure finer.

Corrosion and electrochemical behaviors of 7A09 Al-Zn-Mg-Cu alloy in chloride aqueous solution

The corrosion and electrochemical behaviors of 7A09 Al？Zn？Mg？Cu alloy were investigated in 3.5% NaCl （mass fraction） solution using complementary techniques such as scanning electron microscopy （SEM）, metallographic microscopy and electrochemical measurements. The results show that both pitting corrosion from or around the intermetallic particles and intergranular corrosion are observed after the immersion test due to the inhomogeneous nature of the microstructure of the 7A09 alloy. The preferential dissolution of the anodic Cu-depleted zone along grain boundaries is believed to be the possible cause of intergranular corrosion. The passivation and depassivation of this alloy show significant dependence of immersion time, owing to the formation and dissolution of various passive films on the sample surfaces. Furthermore, the corrosion process and corrosion mechanism were also analyzed.

WC-Ni_3Al-B composites prepared through Ni+Al elemental powder route

In order to develop the liquid phase sintering process of WC-Ni3Al-B composites,the preparation process of WC＋Ni3Al prealloyed powder by reaction synthesis of carbonyl Ni,analytical purity Al and coarse WC powders was investigated.DSC and XRD were adopted to study the procedure of phase transformation for the 3Ni＋Al and 70%WC＋（3Ni＋Al） mixed powders in temperature ranges of 550-1200 °C and 25-1400 °C,respectively.The results demonstrate that the formation mechanism of Ni3Al depends on the reaction temperature.Besides WC phase,there exist Ni2Al3,NiAl and Ni3Al intermetallics in the powder mixture after heat treatment at 200-660 °C,while only NiAl and Ni3Al exist at 660-1100 °C.Homogeneous WC＋Ni3Al powder mixture can be obtained in the temperature range of 1100-1200 °C.The WC-30%（Ni3Al-B） composites prepared from the mixed powders by conventional powder metallurgy technology show nearly full density and the shape of WC is round.WC-30%（Ni3Al-B） composites exhibit higher hardness of 9.7 GPa,inferior bending strength of 1800 MPa and similar fracture toughness of 18 MPa-m1/2 compared with commercial cemented carbides YGR45（WC-30%（Co-Ni-Cr））.

Tortuosity factor for porous FeAl intermetallics fabricated by reactive synthesis

The tortuosity factor is the most critical parameter for the pore characteristic of porous materials. The tortuosity factor for porous FeAl intermetallics was studied based on the Darcy law and Hagen-Poiseuille equation. Porous stainless steel with the same pore structure parameter as porous FeAl was fabricated by powder metallurgy method for comparison. The results show that the tortuosity factor of porous FeAl intermetallics is smaller than that of porous stainless steel when their pore structure parameters are the same. The average tortuosity factor is 2.26 for the porous FeAl material and 2.92 for the porous stainless steel, calculated by Hagen-Poiseuille equation. The reason of the different tortuosity factors for porous FeAl and porous stainless steel was also explored through studying the pore formation mechanisms of the two types of porous materials.

Effect of pore structures on corrosion resistance of porous Ni_3Al intermetallics

Porous Ni3Al intermetallics were fabricated by elemental powder reactive synthesis method, using carbamide powders as space holders. Corrosion behavior of porous Ni3Al intermetallics was investigated in a 6 mol/L KOH solution using electrochemical methods and immersion test. Effect of porous structures on the corrosion behavior of the porous Ni3Al intermetallics was studied. The results indicate that the porous Ni3Al intermetallics with higher porosities suffer more serious corrosion than the ones with lower porosities because the complicated interconnected porous structures and the large true surface areas exist in the samples with a higher porosity. But the corrosion rates of the porous Ni3Al intermetallics are not proportional to the true surface areas. The reason is that the pore size, pore size distribution and pore shape of the porous Ni3Al intermetallics change with the increasing porosity. All the porous Ni3Al intermetallics with different porosities exhibit excellent corrosion resistance in a strong alkali solution.

Phase equilibria of Mg-rich corner in Mg Zn Al ternary system at 300 °C

The phase equilibria and compositions in Mg-rich comer at 300℃ were determined in the Mg-Zn-A1 ternary system through the equilibrated alloy method by using X-ray diffraction （XRD） and scanning electron microscopy （SEM） assisted with energy dispersive spectroscopy of X-ray （EDS）. The results show that there exist three three-phase regions consisted of a-Mg＋Mg17A112（7）＋A15Mg11Zn4（φ）, a-Mg＋Mga2（Al, Zn）49（r）＋A15MgllZn4（φ） and a-Mg＋MgZn＋Mg32（A1, Zn）49（r）, respectively. The intermetallic compounds in equilibrium with a-Mg phase all have large composition ranges, not appear to be linear. At the same time, both zinc and aluminum are soluble in the a-Mg solid solution, with which the compounds are in equilibrium.

Effects of Mn and Sn on microstructure of Al-7Si-Mg alloy modified by Sr and Al-5Ti-B

The effects of Mn and Sn on the microstructure of Al?7Si?Mg alloy modified by Sr and Al?5Ti?B were studied. The results show that the columnar dendrites structure is observed with high content of Sr, indicating a poisoning effect of the Al?5Ti?B grain refinement. In addition, Sr intermetallic compounds distribute on the TiB2 particles, which agglomerate inside the eutectic Si. The mechanism responsible for such poisoning was discussed. The addition of Mn changes the morphology of iron intermetallic compounds fromβ-Al5FeSi toα-Al(Mn,Fe)Si. Increasing the amount of Mn changes the morphology ofα-Al(Mn,Fe)Si from branched shape to rod-like shape with branched distribution, and finally convertsα-Al(Mn,Fe)Si to Chinese script shape. The microstructure observed by transmission electron microscopy (TEM) shows that Mg is more likely to interact with Sn in contrast with Si under the effect of Sn. Mg2Sn compound preferentially precipitates between the Si/Si interfaces and Al/Si interfaces.

Effect of immersion Ni plating on interface microstructure and mechanical properties of Al/Cu bimetal

A nickel-based coating was deposited on the pure Al substrate by immersion plating,and the Al/Cu bimetals were prepared by diffusion bonding in the temperature range of 450-550 ℃.The interce microstructure and fracture surface of Al/Cu joints were studied by scanning electron microscopy（SEM） and X-ray diffraction（XRD）.The mechanical properties of the Al/Cu bimetals were measured by tensile shear and microhardness tests.The results show that the Ni interiayer can effectively eliminate the formation of Al-Cu intermetallic compounds.The Al/Ni interface consists of the Al3Ni and Al3Ni2 phases,while it is Ni-Cu solid solution at the Ni/Cu interce.The tensile shear strength of the joints is improved by the addition of Ni interiayer.The joint with Ni interiayer annealed at 500 ℃ exhibits a maximum value of tensile shear strength of 34.7 MPa.

Review on corrosion-wear resistance performance of materials in molten aluminum and its alloys

The failure caused by the corrosion-wear of molten aluminum and its alloys is one of the main problems in aluminum industry. In this work, the resistance behavior of various materials, including Fe-based alloys, ceramics and corresponding high apparatus of corrosion-wear in molten aluminum and its alloys, were reviewed. The synergistic effect of corrosion and wear was discussed based on corrosion and wear mechanics. The effects of dynamic agitation due to rotating of friction pairs, physical property of liquid metal and size of grain etc., on the corrosion-wear resistance performance were investigated. In addition, the characteristics of corrosion-wear resistance performance of materials in molten aluminum and its alloy were summarized. According to our recent progress referred to kinds of materials, especially a TiA13/Ti3A1C2/A1203 composite, the ceramics/metal composites with a co-continuous structure will be of great advantage in the field of corrosion-wear environment of molten aluminum and its alloys.

Effect of Ce addition on microstructure of Mg-9Li alloy

The as-cast and as-extruded Mg-9Li, Mg-9Li-0.3Ce alloys were respectively prepared through a simple alloying process and hot extrusion. The microstructures of these alloys were investigated by optical microscope （OM）, scanning electron microscope （SEM）, X-ray diffractometer （XRD） and energy dispersive spectrometer （EDS）. The results indicate that Ce addition produces a strong grain refining effect in Mg-9Li alloy. The grain size of the as-extruded alloy reduces abruptly from 88.2 μm to 10.5 μm when the addition of Ce is 0.36%. Mg12Ce is verified and exists inside the grains or at the grain boundaries, thus possibly pins up grain boundaries and restrains the grain growth.

Effects of slurry pack cementation temperature on microstructure and wear resistance of Ti-Al co-deposited coating on copper plated nickel layer

In order to improve the wear resistance properties of copper substrate, a layer of electroplated nickel was firstly deposited on copper substrate, subsequently these electroplated specimens were treated by slurry pack cementation process with a slurry pack cementation mixture composed of TiO2 as titanizing source, pure Al powder as aluminzing source and also a reducer for titanizing, an activator of NH4Cl and albumen （egg white） as cohesive agent. The Ti-Al coating was fabricated on the surface of electro-deposited nickel layer on copper matrix followed by the slurry pack cementation process. The effects of slurry pack cementation temperature on the microstructures and wear resistance of Ti-Al coating were studied. The results show that the microstructure of the coating changed from NiAl＋Ni3（Ti,Al） to NiAl ＋Ni3（Ti,Al）＋Ni4Ti3 to Ni4Ti3＋NiAl, and to NiAl＋Ni3（Ti,Al）＋NiTi with slurry pack cementation temperature ranging from 800 ℃ to 950 ℃ in 12 h. The friction coefficient of Ti-Al coating decreased and the hardness increased with increasing the slurry pack cementation temperature. The minimum friction coefficient was 1/3 and the minimum hardness was 5 times larger than that of pure copper.