引线框架用C194铜合金的铸态组织和加工工艺对电导率的影响

通过添加Fe、P和Zn研究了C194铜合金的铸态组织,设计并选择合理的加工工艺(熔炼、铸造、热轧、固溶处理、冷扎变形、时效处理)来获得导电性能良好的C194引线框架铜合金。结果表明,在时效处理前进行冷轧,可有效提高C194引线框架铜合金的导电性。     

磷含量对Cu-Fe-P合金组织与性能的影响

通过显微硬度及相对电导率测试、光学显微镜和扫描电镜观察,研究了Cu-2.3Fe-0.05P-0.2Zn(C194)合金与Cu-2.3Fe-0.6P-0.2Zn合金冷轧态与时效态的组织与性能。结果表明:添加0.6%P元素,铜合金内部形成大量Fe2P相,一部分固溶到基体,一部分以颗粒形式弥散存在于合金内,尺寸可达10μm,后续热处理难以消除;Cu-2.3Fe-0.6P-0.2Zn合金的初始加工态性能优于C194合金,但基体中Fe溶质原子的浓度低,电导率上升速率变低;微米级Fe2P颗粒会激发再结晶,再结晶软化作用使得Cu-2.3Fe-0.6P-0.2Zn合金耐热性能低于C194合金。对于C194合金,P不宜过量。     

SiC对C194铸态合金组织及性能的影响

研究Si C的加入量对C194合金铸态组织和性能的影响。研究结果表明,Si C对C194合金铸态组织有明显的细化效果,能有效减小铸锭晶粒的尺寸。通过Image Pro Plus软件统计得出,当Si C添加量为0.4%时晶粒细化效果最佳,比未添加Si C的合金晶粒尺寸减小了83.1%。合金硬度也得到提高,Si C添加量为0.8%时硬度达到最高值为HB76.7,比未添加时提高了20%。     

时效处理对冷轧C194铜合金性能的影响

研究了不同时效工艺对冷轧C194铜合金硬度、电导率、强度和伸长率等的影响,给出了C194铜合金较佳的时效工艺。结果表明,C194铜合金较佳的时效工艺为450℃×60min,其抗拉强度为582 MPa,伸长率为15.3%,硬度(HV)为170,电导率为41.47 MS/m,硬度、电导率、强度较连续挤压态与冷轧态的有明显提高,但伸长率下降。合金第二相小颗粒的数量较连续挤压态有明显增加,且弥散分布在基体内部,尺寸为10~20nm。较大的第二相颗粒数量较挤压板材的变化不大,第二相析出物及长大相为Fe3P化合物。     

引线框架用C194铜合金工艺的研究

对国内外引线框架用C194合金的成分及性能进行了对比,分析了不同合金含量对材料性能的影响,随后进行了合金熔铸工艺的研究,用SEM分析了微观组织。结果表明,C194合金性能上的差距是由于铸坯中产生的5-10μm左右的粗大析出颗粒造成的,但这些颗粒的形成不是主要由于元素P、Zn合金元素含量的不同造成的,也不是由于铸造温度及速度的变化产生的,而是由于Cu—Fe和Cu—P中间合金的添加方法不正确带来的。因此,在合金熔炼过程中,Cu—Fe和Cu-P中间合金一定在熔体完全熔化后同时加入。     

添加Mn对高碳铬铁铸渗复合材料组织的影响

利用铸渗工艺在ZG45钢表面获得高锰高碳的铬铁铸渗层,通过改变铸渗合金粉中锰含量,研究了锰对铸渗表面复合材料组织均匀性及性能的影响。结果表明:获得的铸渗层厚度在6 mm以上;当自制合金粉末中锰含量为11%时,获得的铸态组织中碳化物以菊花状弥散均匀地分布在奥氏体基体中,碳化物主要有Cr7C3、Fe3C、Cr23C6等,铸渗层致密,无气孔,铸渗层与基体之间为冶金结合,且此时硬度达到最大值HRC56。     

C19400铜合金组织的研究

C19400铜合金是一种可用来制作引线框架的材料。采用金相显微镜、X射线衍射仪和扫描电镜研究了C19400铜合金铸态和轧制态的显微组织。结果表明:铸态C19400铜合金存在典型的树枝晶组织,树枝晶组织中有弥散的Fe_2P和碳元素偏聚;轧制态C19400铜合金存在典型的织构,还有α-Fe,RD面上有大颗粒的Fe_2P和碳元素偏聚,大颗粒的Fe_2P是在轧制过程中形成的,轧制不能消除碳偏析。     

铁含量对铸态铝铁合金力学性能及组织的影响

采用拉伸试验机、光学显微镜、扫描电镜、X射线衍射仪和三维纳米X射线显微镜等分析手段研究了铁含量对铸态Al-Fe合金力学性能和微观组织结构的影响。结果表明:随着铁含量的增大,铸态Al-Fe合金抗拉强度和屈服强度增大,断后伸长率下降。大量的球状Al₆Fe析出相和杆状Al₃Fe析出相分布在试验合金铸锭晶界附近,与铸态Al-1.8Fe合金相比,铸态Al-2.6Fe合金具有更小尺寸的晶粒和更大尺寸的Al₃Fe析出相。尺寸更小的晶粒导致铸态Al-2.6Fe合金的强度高于铸态Al-1.8Fe合金,而铸态Al-2.6Fe合金伸长率更低的主要原因是具有更大尺寸的脆性Al₃Fe析出相。     

铜模喷铸Fe_(100-x)Ga_x(15≤x≤30)合金的磁致伸缩

采用铜模喷铸法,制备Fe100-xGax(x=15,19,23,27.5,30)合金。实验结果表明铜模喷铸有利于改善低Ga(15≤x<23)Fe100-xGax合金的磁致伸缩,却大幅降低了高Ga(23≤x≤30)Fe100-xGax合金的磁致伸缩。以Fe81Ga19和Fe72.5Ga27.5合金为例,喷铸态Fe81Ga19样品的饱和磁致伸缩比800℃淬火态提高了7%;而喷铸态Fe72.5Ga27.5样品的饱和磁致伸缩为6.1×10-5,仅是800℃淬火态的60.4%。此外,淬火态Fe72.5Ga27.5样品的饱和磁化强度为131.21A·m2·kg-1,也高于喷铸态(126.21A·m2·kg-1)。     

电冶熔铸工艺制备的DGJW30复合材料的组织研究

采用电冶熔铸方法制备了DGJW30复合材料，研究了其铸态组织。结果表明，该复合材料的组织为珠光体、共晶莱氏体和未溶碳化钨，具体相为Fe3 W3 C、W2 C、WC、奥氏体、α-Fe和Fe3 C。共晶莱氏体由Fe3 W3 C和残留奥氏体组成。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.