配碳量对含铬型钒钛烧结矿质量的影响

通过烧结杯试验,研究不同配碳量对含钛型钒钛烧结矿质量的影响规律。结果表明,随配碳量增加(2.8~4.0),含铬型钒钛烧结矿的液相生成量增加,垂直烧结速度、烧成率降低,成品率先上升后降低;不同配碳量的含铬型钒钛烧结矿的矿物组成基本相同,含铁矿物均以磁铁矿和赤铁矿为主,粘结相为铁酸钙、硅酸盐、玻璃质等;随配碳量上升,磁铁矿、硅酸盐和钙钛矿含量增加,赤铁矿和铁酸钙含量减少;随配碳量增加,含铬型钒钛烧结矿的转鼓强度先上升后下降,还原粉化性能上升,还原性下降,烧结矿适宜配碳量为3.6%。     

高密度钨合金性能的计算机数值模拟研究──钨含量对合金性能的影响

提出了一个钨合金的组织结构模型,在一定的假设条件下用有限元方法和计算机数值模拟研究了钨合金力学性能和钨含量的关系。结果表明;随钨含量增加,合金屈服强度提高,但弹性变形量和延伸率均降低。当钨含量＜85％（质量分数,下同）时,合金抗拉强度随钨含量增加而增加;当钨含量＞85％时,合金抗拉强度随钨含量增加而降低,在钨含量为85％附近达到最大值。在低钨含量合金中（＜90％）,高应力主要集中在钨颗粒中,随钨含量增加,粘结相中应力水平降低;在高钨含量合金中钨颗粒和粘结相中应力水平基本相同,随钨含量增加,粘结相中应力水平增加。     

稀土元素对硬质合金钴粘结相影响的研究

利用配备能谱仪（EDS）的透射电镜（TEM）、扫描电镜（SEM）和X射线衍射仪（XRD）对添加稀土元素前后的YT14硬质合金的钴粘结相进行了研究．结果表明，微量稀土元素加入后，钴粘结相中W、Ti元素的固溶量提高；钴粘结相中f．c．c－Co相的点阵常数和所占的体积分数均较未加稀土的合金增大了．根据实验结果对稀土元素强化硬质合金的机理进行了探讨．     

WC粒度、配碳量对WC-9%Ni硬质合金组织与性能的影响

采用Ni作为黏结相，通过粉末冶金工艺制备WC-9%Ni(质量分数)硬质合金，通过光学显微镜、硬度仪、X衍射分析仪等仪器，研究WC粒度、配碳量对WC-9%Ni硬质合金组织与性能的影响。结果表明：合金晶粒度受配碳量的影响较小，随WC粒度增大而增大；合金硬度随配碳量增加而降低，随WC粒度增大而降低。费氏粒度1.78μm的WC与费氏粒度2.4μm的WC制备的合金洛氏硬度最高分别为88.6HRA、87.5HRA，维氏硬度HV₃₀最高分别为11.9、11.0 GPa。合金矫顽磁力与比饱和磁化强度极低，合金断裂韧性随配碳量的增加而降低，随WC粒度增加而增加，抗弯强度受配碳量影响较小，随WC粒度增加而降低。     

碳含量对Ti(C,N)基金属陶瓷组织和性能的影响

综述了添加碳量对金属陶瓷组织和性能的影响。在一定范围内,随碳添加量的增加,组织细化,粘结相中Mo、W、Ti等元素的溶解度降低;添加碳量过少或过多都会使材料的相组成离开两相区,生成第三相η相(TiNi3)或游离碳,而第三相的生成会显著降低金属陶瓷的机械性能。     

中间退火温度对Fe—Mn—Si—Cr—Ni—C系合金记忆效应的影响

研究了热机械循环训练的中间退火温度对Ｆｅ－Ｍｎ－Ｓｉ－Ｃｒ－Ｎｉ－Ｃ系合金形状记忆效应的影响，结果表明，当碳含量小于０．１２％时，合金的最佳中间退火温度随碳含量的增加而略有提高，但当碳含量大于０．１２％后，碳含量的增加显著提高合金的最佳中间退火温度。只要中间退火温度适当，热机械循环训练能显著提高合金的ＳＭＥ，训练２￣３次，合金的ＳＭＥ有大幅度提高；但继续训练，提高不大。     

中间退火温度对Fe-Mn-Si-Cr-Ni-C系合金记忆效应的影响

研究了热机械循环训练的中间退火温度对Ｆｅ－Ｍｎ－Ｓｉ－Ｃｒ－Ｎｉ－Ｃ系合金形状记忆效应（ＳＭＥ）的影响，结果表明：当碳含量小于０．１２％时，合金的最佳中间退火温度随碳含量的增加而略有提高；但当碳含量大于０．１２％后，碳含量的增加显著提高合金的最佳中间退火温度。只要中间退火温度适当，热机械循环训练能显著提高合金的ＳＭＥ；训练２～３次，合金的ＳＭＥ有大幅度提高；但继续训练，提高不大。     

Zr-Sn-Nb-Fe合金中铌的存在方式及其与热处理的关系

用 SEM 的波谱(WD)分析手段,定性研究了合金元素铌在 Zr-Sn-Nb-Fe 合金中的存在方式及其与中间退火工艺的关系。研究结果表明添加的合金元素铌主要存在于 Laves 相中,并且随中间退火温度升高,第二相中铌含量增加。铌在 α-Zr 中的含量随退火温度升高而降低,可降低至小于 1×10-4,这与二元 Zr-Nb 合金中合金元素铌的固溶度随温度升高而增加明显不同。铌和铁、铬共存于锆合金中时,将与铁、铬一起优先形成沉淀相,导致合金元素主要存在于第二相中,并出现其在 α-Zr 中固溶量随退火温度升高而降低的现象;其原因可归结为随退火温度升高铌扩散能力增加,从而导致在第二相中含量增加。     

钛制机动艇船台

研究了配碳量与Ｎｉ／Ｃｏ比对ＷＣ－９（Ｎｉ－Ｃｏ）硬质合金抗率强度的影响。实验结果表明：ＷＣ－３Ｎｉ－６Ｃｏ的配碳量是６．０４ｗｔ％时，其抗弯强度与ＷＣ－９Ｃｏ硬质合金相当；Ｎｉ的分布均匀性对抗弯强度的影响极其重要，粗粒Ｎｉ粉或（和）较多η相的存在都会使硬质合金形成脆性断裂，直接影响合金的抗弯强度。     

Mo含量对烧结WC-CoCrCuFeNiMo_x硬质合金性能的影响

以CoCrCuFeNiMo_x高熵合金粉末为粘结相,通过粉末冶金压制、烧结工艺制备WC-6 mass%CoCrCuFeNiMo_x硬质合金,并研究了高熵合金粘结相中Mo含量的不同对合金性能的影响。结果表明,WC-6 mass%CoCrCuFeNiMo_x硬质合金在1380℃烧结后所获得的合金物相主要由WC相和FCC面心立方相组成。随着烧结温度的提高,粘结剂的FCC相消失,其主要原因可能是温度升高,高熵合金粘结相中各元素的扩散得到加强,且Mo的加入使元素间的扩散混乱,致使其出现无序相,导致XRD探测不到具体的FCC面心相。此外,随着Mo含量的增加,粘结相中的混乱度增加,致使其溶解的W和C原子数量降低,减缓WC溶解-析出速率,有效抑制了WC晶粒的长大,使WC-6 mass%CoCrCuFeNiMo_x硬质合金的WC晶粒尺寸随Mo含量的增加呈变小的趋势。同时,Mo含量的增加会强化粘结相,使合金的硬度及抗弯强度提高。     

Effects of carbon content and solidification rate on thermal conductivity of grey cast iron

The thermal conductivity or diffusivity of pearlitic grey irons with various carbon contents is investigated by the laser flash method. The materials are cast in controlled thermal environments and produced in three dissimilar cooling rates. The cooling rate together with the carbon content largely influence the thermal conductivity of grey iron. Linear relationships exist between the thermal conductivity and the carbon content, the carbon equivalent and the fraction of former primary solidified austenite transformed into pearlite. The work shows that optimal thermal transport properties are obtained at medium cooling rates. Equations describing the thermal conductivity of pearlite,solidified as pre-eutectic austenite, and the eutectic of grey iron are derived. The thermal conductivity of pearlitic grey iron is modeled at both room temperature and elevated temperature with good accuracy.     

Effect of Alloying Elements on Thermal Diffusivity of Gray Cast Iron Used in Automotive Brake Disks

The purpose of this work was to experimentally investigate the thermal diffusivity of four different gray cast iron alloys, regularly used to produce brake disks for automotive vehicles. Thermal diffusivity measurements were performed at temperatures ranging from room temperature to 600 °C. The influence of the thermal conductivity on the thermomechanical fatigue life is also briefly presented. The measurements were sensitive to the influence of the carbon equivalent and alloying elements, such as molybdenum, copper and chromium. Molybdenum, unlike copper, lowered the thermal diffusivity of the gray cast iron, and alloy E (without molybdenum), besides presenting a relatively low carbon equivalent content and an increase in the values of the thermal diffusivity, presented the best performance during the thermomechanical fatigue. The molybdenum present in alloys B and C did not fulfill the expectations of providing the best thermomechanical fatigue behavior. Consequently, its elimination in the gray cast iron alloy for this application will result in a significant economy.     

硬质合金注射成形脱脂过程中的碳含量控制

研究了不同脱脂气氛 (不同比例N2 与H2 的混合气体 )和脱脂方法 (热脱脂、溶剂脱脂 热脱脂、冷凝蒸汽脱脂 热脱脂 )对PIM硬质合金脱脂坯及合金碳含量的影响。结果表明 :N2 热脱脂粘结剂容易以炭黑的形式残留在脱脂坯中 ,造成合金增碳 ;H2 热脱脂导致合金脱碳 ;75 %N2 2 5 %H2 (体积分数 )混合气体热脱脂既能有效地脱除粘结剂 ,又能保证合金碳含量相对稳定 ;溶剂脱脂和冷凝溶剂脱脂能显著缩短脱脂时间 ,而且由于高温保持时间短 ,在后续热脱脂过程中采用H2 作保护气也可获得满意的碳含量 ,说明该方法对工艺条件的适应性强。通过调整热脱脂高温保持时间 ,可在一定范围内对脱脂坯的碳含量进行调整 ,说明过程的可调控性好。与溶剂脱脂相比 ,冷凝蒸气脱脂粘结剂脱除率更高 ,脱脂坯有较高的强度 ,有效地防止了脱脂坯软化变形的现象。     

Effect of carbon on the coefficient of thermal expansion of as-cast Fe−30wt.%Ni−12.5wt.%Co−×C invar alloys

The segregation (distribution) of nickel and the composition of its constituents influence the low thermal expansion characteristics (Invar effect) in Fe?30 wt.% Ni?12.5wt.% Co?×C Invar alloy. The change of coefficient of the thermal expansion and magnetic properties were studied as an aspect of carbon addition causing the segregation of Ni in primary austenite of as-cast Fe?30wt.% Ni?12.5wt.% Co Invar alloy. The coefficient of thermal expansion of Fe?30 wt.% Ni?12.5 wt.% Co?×C Invar alloy showed its lowest value at 0.08 wt.% carbon, increased with increasing carbon content in the range of 0.08–1.0 wt.%C, kept constant at 1.0–2.0 wt.%C and decreased at carbon higher than 2.0 wt.%. The effective distribution of the coefficient of nickel in as-cast Fe?30 wt.% Ni?12.5 wt.% Co?×C Invar alloy increased with increasing carbon content. The volume fraction of the γ phase of Fe?30 wt.% Ni?12.5 wt.% Co?×C alloy increased with increasing carbon content. The microstructure of Fe?30 wt.% Ni?12.5 wt.% Co?×C alloy changed with the carbon content was independent of the coefficient of thermal expansion. The Curie temperature changed linearly with the carbon content and was similar to the change of the coefficient of thermal expansion. Moreover, the coefficient of thermal expansion decreased when the ratio of saturation magnetization to Curie temperature (σ_s/T_c) increased, decreasing the Curie temperature and showed a specific relationship with the magnetic properties of the Fe?30 wt.% Ni?12.5 wt.% Co?×C Invar alloy.     

Powder processing of FeAl sheets by roll compaction

Powder metallurgical processing techniques were employed to manufacture 0.2 mm thickness of iron aluminide sheets based on Fe-40 at% Al using water atomized powder of an FeAl alloy containing C, B, Mo and Zr as alloying elements. Powders of FeAl mixed with polymeric binders were roll compacted using two counter rotating rolls to a thickness of approximately 0.66 mm. Roll compacted sheets were then debindered in nitrogen using a two stage debindering cycle over a period of several hours to effectively decompose the binder. Debindered sheets were vacuum sintered prior to cold rolling them for densification in several different stages. The properties of the FeAl sheets are dependent on the processing temperature, Al content of the final sheet, oxygen content, and the microstructure. Sheets exhibit fine microstructure with a dispersion of Al₂O₃ particles throughout the matrix. Variation of electrical resistivity, specific heat, thermal expansion, and thermal diffusivity with variation of temperature is presented, and compared with 304 steel.     

Influence of process parameters for coating of nickel–phosphorous on carbon fibers

The nickel–phosphorous (Ni–P) coating on carbon fiber was studied, using sodium hypophosphite as a reducing agent in alkaline medium. The effects of process parameters such as time, stabilizer concentrations, pH of the plating bath and plating bath's temperature on the electroless Ni–P coating efficiency were investigated. Structural study using X-ray diffraction (XRD) indicates that nickel deposition rate increases with increasing coating time and temperature. The nickel (Ni) recovery efficiency decreases with an increase of stabilizer concentration. From scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), it has been confirmed that the coating thickness and nickel content increase with an increase of coating time and temperature. The bath temperature of 25 °C, pH of 9, and stabilizer concentration of 25 g/L is good to get a good and uniform coating of Ni on carbon fiber. Thermal stability was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). From TGA study it is evident that the nickel coating increases thermal stability of the nickel-coated carbon fiber. I–V (current vs voltage) measurement shows Ni-coated fiber is more conducting in nature.     

Rapid Hydrogen Transportation Along Grain Boundary in Nickel

The permeability and diffusivity of hydrogen in directionally solidified polycrystalline and single crystal nickel foils were measured by gas permeation method.The results showed that both hydrogen diffusivity and permeability were higher in directionally solidified nickel specimen than those in single crystal one at the temperature ranging from 300 to480 °C,and confirmed the existence of short-circuit diffusion along the grain boundaries(GBs) in the directionally solidified nickel.The results suggested that the rapid diffusion along GBs was more obviously characterized in terms of higher permeability rather than higher diffusivity.The contribution of grain boundary to hydrogen transportation was represented by the differences of diffusivity(and permeability) in single crystal nickel and directionally solidified nickel.By modifying the Fick's first diffusion law and counting the grain boundary density,the hydrogen diffusivity and permeability of rapid diffusion along GBs were calculated.The results suggested both the diffusivity and permeability fit the Arrhenius relationship well at different temperature.     

粘结剂组成对粘结剂和喂料热性能的影响

研究制备了PW，BO，OP3大系列10种组成的粘结剂及相应10种W-Ni-Fe粉末与粘结剂的混合料。并采用热失重-差热分析(TGA-DTA)分析了粘结剂和喂料的热性能。研究结果表明，粘结剂组成对粘结剂和喂料的热性能如熔点、热分解温度和热分解曲线有很大的影响。通过此变化可以更为准确地确定不同粘结剂组成的喂料中的粘结剂脱除工艺和脱除方式。     

Effect of carbon content on the Curie temperature of WC-NiFe cemented carbides

We have investigated the effect of the carbon content on the Curie temperature of a cemented carbide composite material with a Ni-Fe alloy as the binder phase and WC as the hard phase. In the carbon concentration range from 5.72 to 5.83 wt% carbon, which covers the interval where WC coexists with fcc Ni-Fe without other phases (the ‘carbon window’), the Curie temperature rises from 200 to 527 °C. This result indicates the possibility to use the Curie temperature to determine the carbon balance in the system. With thermodynamic calculations and kinetic simulations we can quantitatively establish the correlation between the carbon and tungsten content of the binder phase and the Curie temperature. This strong compositional effect on the Curie temperature is quantitatively very different from the conventional Co-based cemented carbides, with Curie temperatures of about 950–1050 °C.     

Carbide grain growth in cemented carbides sintered with alternative binders

Cemented carbides are composites made of a hard refractory ceramic phase and a ductile binder, most commonly WC and Co, respectively. Since the use of cobalt in the hard metal industry is questioned by the new European regulation on chemicals, extensive research has been done to develop new grades based on a Co-Ni-Fe binder. With similar mechanical, physical properties and affinity to C and W, nickel and iron are the best candidates for an efficient binder in cemented carbides. As mechanical properties are strongly dependent on the materials microstructure, and especially on the WC grain size, understanding the effect of the binder on the final microstructure is crucial.In this work, the carbide grain growth behaviour of WC-M alloys (M = Co, Ni, Fe) with different carbon contents is discussed from qualitative and quantitative microstructural analyses. Whereas grain growth is more or less inhibited in WC-Fe alloys, increasing carbon content promotes grain growth in WC-Co and WC-Ni alloys, with a slight abnormal grain growth in case of Ni binder. Different mechanisms for grain growth are discussed, in relation with the observed morphology of WC grains after sintering.