Fracture Resistance Factors of Iron-Based Hard Alloys

The structural factors that determine the difference between the fracture strengths of iron-based hard alloys are estimated using the means of digital recording and measurement of structure and fracture surface images.     

Iron-Based Amorphous Metals: High-Performance Corrosion-Resistant Material Development

An overview of the High-Performance Corrosion-Resistant Materials (HPCRM) Program, which was cosponsored by the Defense Advanced Research Projects Agency (DARPA) Defense Sciences Office (DSO) and the U.S. Department of Energy (DOE) Office of Civilian and Radioactive Waste Management (OCRWM), is discussed. Programmatic investigations have included a broad range of topics: alloy design and composition, materials synthesis, thermal stability, corrosion resistance, environmental cracking, mechanical properties, damage tolerance, radiation effects, and important potential applications. Amorphous alloys identified as SAM2X5 (Fe_49.7Cr_17.7Mn_1.9Mo_7.4W_1.6B_15.2C_3.8Si_2.4) and SAM1651 (Fe₄₈Mo₁₄Cr₁₅Y₂C₁₅B₆) have been produced as meltspun ribbons (MSRs), dropcast ingots, and thermal-spray coatings. Chromium (Cr), molybdenum (Mo), and tungsten (W) additions provided corrosion resistance, while boron (B) enabled glass formation. Earlier electrochemical studies of MSRs and ingots of these amorphous alloys demonstrated outstanding passive film stability. More recently, thermal-spray coatings of these amorphous alloys have been made and subjected to long-term salt-fog and immersion tests; good corrosion resistance has been observed during salt-fog testing. Corrosion rates were measured in situ with linear polarization, while the open-circuit corrosion potentials (OCPs) were simultaneously monitored; reasonably good performance was observed. The sensitivity of these measurements to electrolyte composition and temperature was determined. The high boron content of this particular amorphous metal makes this amorphous alloy an effective neutron absorber and suitable for criticality-control applications. In general, the corrosion resistance of such iron-based amorphous metals is maintained at operating temperatures up to the glass transition temperature. These materials are much harder than conventional stainless steel and Ni-based materials, and are proving to have excellent wear properties, sufficient to warrant their use in earth excavation, drilling, and tunnel-boring applications. Large areas have been successfully coated with these materials, with thicknesses of approximately 1 cm. The observed corrosion resistance may enable applications of importance in industries such as oil and gas production, refining, nuclear power generation, shipping, etc.     

非晶合金的制备

综述了制备非晶的各种方法,介绍了大块非晶的制备途径,对一些方法特点进行了讨论,并对它们进行了初步对比.     

Crystallization of Amorphous Alloys

Crystallization of amorphous alloys is compared with conventional solidification of melts. Taking account of the temperature dependence of crystal nucleation and growth rates, the links between the two processes are explored. The fundamentals of nucleation and growth kinetics in amorphous alloys are reviewed. It is shown that the crystallization of amorphous alloys can be exploited (1) to obtain ultrafine grained microstructures with useful properties and (2) to elucidate nucleation mechanisms in conventional grain-refining practice. This article is based on a presentation made at the “Analysis and Modeling of Solidification” symposium as part of the 1994 Fall meeting of TMS in Rosemont, Illinois, October 2–6, 1994, under the auspices of the TMS Solidification Committee.     

Composition Range of Amorphous Mg-Ni-Y Alloys

Based on the thermodynamic point of view, a method for predication of the composition range of amorphous ter-nary alloys was proposed. The composition range of amorphous ternary alloys is determined by the comparison of the excess free energy of the amorphous alloy and the free energy of competing crystalline states. The free energy is extrapolated from the data of three binary alloys by using Toop‘s model. The method was applied to predict the composition range of amor-phous Mg-Ni-Y alloys. The theoretical results are in good agreement with the available experimental results. It indicates that the present method can be used to predict the composition range for amorphous ternary alloys.     

铁基非晶态合金的退火脆性

本文研究Fe₈₀B_20-xSi_x(x=6,8,10,12)非晶态合金的退火脆性规律,给出了合金成分原料纯度,薄带厚度以及薄带表面状态对非晶态合金退火脆性的影响。铁基非晶态合金在低温退火过程中已明显变脆。这种退火脆性是由非晶态合金亚稳特性决定的结构弛豫所致。     

Investigation of Mechanical Properties of High-Density Iron-Based Alloys with Nanosized Additions

Metallurgist - Detailed analysis is provided for results of studying mechanical properties of alloys based on iron and nanodispersed particles of nickel oxide, copper oxide, and silicon nitride...     

Thermal Expansion Behavior of Amorphous Fe-Si-B Alloys

 To study the thermal expansion of amorphous Fe Si B alloys, the amorphous Fe78Si9B13 and Fe735Nb3 Cu1Si135B9 and their crystallized alloys were detected using thermal dilatometer. The results indicate that at the same temperature, the relative length change (ΔL/L0) values of the two Fe based amorphous alloys decrease with increasing heating rate, but those of their crystallized alloys show an opposite trend. It is concluded that the effect of heating rate on the ΔL/L0 of amorphous and crystallized alloys is related to free volume and defects, respectively.     

Production of Amorphous Alloys for Cybernetic Circuits

The ways in which the manufacturing conditions affect the magnetic (domain) structure of amorphous alloy strip produced on cooled disks are studied. On that basis, the physical properties of the alloys may be optimized for their intended use.     

镁基非晶电极合金的容量衰减机制探讨

采用熔体快淬法制备了(Mg70.6Ni29.4)100-xNdx(x=2,5,10,15)电极合金带,用恒流充放电的方法在三电极电池测试仪上测定其电化学循环性能。用X射线衍射仪、场发射扫描电镜和高分辨电镜对合金在充放电循环过程中的组织结构变化进行了动态检测。结果表明:(Mg70.6Ni29.4)90Nd10非晶电极合金拥有最高的放电容量(580.5 mAh·g-1),经过20个循环以后,合金表面存在严重的氧化(含氧量为26.7%)和开裂粉化现象;在充放电循环过程中,合金内部逐渐形核长大,形核的初生相NdMg2Ni9最终转化为Mg2Ni,α-Mg和Nd2H5相;非晶态Mg-Ni-Nd电极合金在充放电循环过程中放电容量的衰减来自于内外两个方面的综合效应:合金表面碱液的氧化腐蚀和开裂粉化以及非晶合金的晶化导致其贮氢机制失效,反应动力学性能下降,从而引起放电容量的衰减。     

非晶态Ni-P合金在碱性介质中的阳极行为

用动电位极化方法研究了3种不同化学镀工艺得到的Ni-P非晶态合金镀层,在1mol/1NaOH碱性介质中的阳极极化行为,并通过XPS分析了不同极化电位下的表面膜.结果表明:在所研究的体系中不存在随P增加阳极溶解电流下降的规律;尽管合金表面存在H₂PO₂^-和PO₄^-离子,但并没有有效地抑制Ni-P合金的阳极溶解。P的强烈的水化作用可能是导致非晶态Ni-P合金的阳极溶解电流比纯Ni更大的主要原因。     

非晶态铝锰合金电镀的反应机理

循环伏安法证明,二氯化锰浓度和温度对铝-锰电沉积的影响极显著,在静止的熔盐中,较高的二氯化锰浓度和较低的温度有利于形成单一的非晶铝-锰相。恒电位法研究证明,非晶铝-锰的电沉积时,其成核速度很小,而且具有二维生长的特征,所以缺陷少、性能好。     

Evolution and Removal of Inclusions in Fe-Based Amorphous Alloys

Metallurgical and Materials Transactions A - Fe-based amorphous alloys generally suffer from deteriorated glass forming ability and soft magnetic properties due to the impurities in industrial raw...     

机械合金化法制备Cu-Ti-Zr基非晶合金

采用机械合金化法成功制备Cu₄₀Ti_60-xZr_x(x=0,10,30,50)非晶合金.研究Cu-Ti-Zr合金粉末由晶态向非晶态转变过程中的组织结构变化,探讨非晶合金的形成机制,以及非晶合金的热稳定性和晶化产物.结果表明,非晶合金直接从初始元素得到,在反应过程中没有金属间化合物出现,非晶化过程可以由间隙扩散模型来解释.Cu₄₀Ti_xZr_y非晶粉末的DSC分析表明,随着Ti含量的降低和Zr含量的升高,非晶粉末的晶化温度T_x逐渐升高,对非晶粉末在相应的T_x温度附近退火15min后发现,Cu₄₀Ti₃₀Zr₃₀合金没有析出相,Cu₄₀Ti₁₀Zr₅₀析出了Zr₂Cu,Cu₄Ti和少量的一些未知相.     

Effect of Cerium on the Properties of CuPNiSn Amorphous Alloys

CuPNiSn amorphous alloys are good brazing materials at medium temperature for replacementof silver bearing brazing materials.The crystallization temperature,wettability,tensile strength of Cu-Cujoints and the microstructure of joints for three compositional series are reported.Some rare earth elementswere added in two series.It has been found that grains are refined and the tensile strengths increase as in-creasing rare earth content.The results also show that the brittle fracture turns to plastic one for the jointswith reducing amount of(Ni+Sn),and the tensile strength is increased.     

Amorphous FeNiCoCuSiBCr Alloys with Superior Direct Current Tolerant Characteristics

Amorphous Fe62-xNi19CoxCu0.1Si3.8B14Cr1.1(x=0,1,5,10)ribbons were annealed under magnetic field and tensile stress,respectively,and their magnetic properties were investigated.Fe73.5Cu1Nb3Si15.5B7 and Fe66Ni10-Cu1Nb3Si11B9 nanocrystalline alloy ribbons were also fabricated for comparison.Excellent DC tolerant property was obtained in the amorphous FeNiCoCuSiBCr ribbons after thermomagnetic treatment and the constant permeable property was improved with increasing Co content.The relative permeability was constant up to the DC bias field of approximately 6×10-4,9×10-4,and 10×10-4 T and the values of relative permeabilityμrwere 1 650,1 200,and 1000 with the Co content being 0,5at.%,and 10 at.%,respectively.Besides,stress-annealed FeNiCoCuSiBCr alloy ribbons were proved to exhibit positive saturation magnetostriction constantλs.     

铁基钴基非晶合金中硼的分光光度测定

本文应用新的显色剂１－（２－羟基－３－甲氧基苯甲醛缩氨基）－８－羟基－３，６－萘二磺酸，直接光度法测定基钴基非晶合金中硼，获得了满意的结果。