DZ417G定向高温合金的熔炼工艺

对DZ417G定向高温合金的熔炼工艺进行了研究,研究了拉晶速率以及碳、硼和钒元素含量对合金组织和高温拉伸及持久性能的影响。结果表明:拉晶速率在5.9⁶.5 mm·min^-1时,合金具有较高的持久寿命及抗拉强度和屈服强度;硼含量增加,对合金抗拉强度、屈服强度、持久寿命及塑性整体影响不大;钒元素质量分数为0.8%时,合金的拉伸性能及持久寿命最佳;碳元素质量分数在0.18%⁰.19%时,合金性能最佳。     

TC18钛合金的组织和性能与热处理制度的关系

通过三因素三水平正交设计方法研究了两阶段退火热处理制度的三个温度阶段对TC18钛合金性能、组织的影响,定量分析了合金热处理温度变化对总体性能的影响,结果表明,在本文试验条件下可通过提高中温温度、降低低温温度来提高合金的强度,降低高温温度、提高低温温度可改善合金的塑性,通过降低高温温度或中温温度可提高合金的冲击韧性,显微组织分析表明,TC18钛合金的强度主要受未转变β组织及在其上产生的次生αs相的总的含量、次生αs相的含量、形状的控制;合金的塑性受初生αp相形状及次生αs相的数量、形状控制;合金的冲击韧性受初生αp相的含量及形状控制.     

超细及纳米硬质合金中碳含量的变化及对组织性能的影响

对于硬质合金而言,碳含量对合金的组织性能有重要影响.介绍了制备超细及纳米硬质合金时影响碳含量变化的因素,包括粉末的制备工艺、烧结工艺、钴含量以及抑制剂和成形剂等.综述了碳含量变化对组织性能的影响,其中碳含量过高会出现石墨相,过低会出现脱碳相,碳含量过高或过低都会降低合金的力学性能.     

Al-Li-Mg-Zr合金组织结构与性能的关系

本文研究了两种 Mg 含量的 Al-Li-Mg-zr 合金组织结构及其性能。结果表明,Mg 是一重要的固溶强化元素,它对 Al-Li-Mg-Zr 合金时效硬化趋势没有影响;Mg 含量增加,合金在各时效状态下强度和硬度均提高,合金中析出的δ′相粗化速率加快。但塑性变化则正好相反,高 Mg合金延伸率较低,与其他时效制度相比,两合金在峰值时效时塑性最低。合金的拉伸断口为穿晶加沿晶混合形式。     

Al和Mo含量对热等静压制备的FeCrAlMo合金组织及拉伸性能的影响

FeCrAl合金由于具有良好的高温抗氧化性能和力学性能而广泛应用于高温和氧化性气氛环境。本研究通过粉末热等静压制备出Fe-22Cr-3Al-3Mo和Fe-22Cr-2Al-5Mo两种成分的合金,对粉末的显微组织、热等静压后两种成分合金的组织及拉伸性能进行对比分析,结果表明:Fe-22Cr-3Al-3Mo合金20℃时的强度和塑性都高于Fe-22Cr-2Al-5Mo合金,而500℃时的强度和塑性都低于Fe-22Cr-2Al-5Mo合金;Fe-22Cr-3Al-3Mo合金中析出相主要为分布在晶界及晶内的细小AlN相及少量粗大的富Cr相,Fe-22Cr-2Al-5Mo合金中析出相主要为大尺寸的富Cr碳氧化物;Al含量降低、Mo含量增加,晶界形成较多的大尺寸富Cr相,导致Fe-22Cr-2Al-5Mo合金在20℃时塑性较差。     

热处理制度对Al—Li合金显微组织和力学性能的影响

通过显微组织观察和室温拉伸实验,研究了3种不同的热处理制度对1种Al-Li-Cu-Mg-Zr合金组织和性能的影响。实验结果表明,T_8处理可同时提高合金的强度和塑性;ITMT处理可改善合金的塑性,但对强度的改善不大;采用T_6处理时,合金的强度和塑性都较低。分析了热处理工艺、显微组织和性能之间的关系。     

Fe含量对Ti80合金显微组织和性能的影响

研究了不同Fe元素含量（0.04%~0.41%,w）对Ti80合金显微组织和性能的影响。结果表明:增加Fe含量,可以提高Ti80合金室温强度。Fe元素含量每增加0.2%,合金强度提高约20 MPa,但对合金塑性与冲击性能无明显影响。Fe元素对合金组织形态有影响,当Fe含量提高至0.41%时,α相由球状转变为长条状。30 d海水腐蚀试验周期内,Fe元素的加入降低了Ti80合金的开路电位,导致合金在天然海水浸泡和5 m/s流速条件下平均腐蚀速率增大,耐海水腐蚀性能有所下降,但与正常Ti80合金仍处于同一数量级。      

Fe-Cr-Al系应变电阻合金的加工性

铁铬铝为基的合金,目前已被广泛地应用作高温应变计的材料。这类合金可以在2。~800℃范围应用。但是,由于化学成分的不同,即铬和铝的含量的不同,显著地影响着高温应变计材料的使用温度范围和加工性能。本文首先简述了合金主要化学成分、合金"纯度"以及其它添加元素对合金加工性的影响效果。对铁铬铝合金而言,如果严格控制温度和加工工艺,含16一27终Cr、4.5一7多Al的合金,能够进行热加工和冷加工;合金的"纯度"对合金的塑性亦产生较大的影响。特别是含碳量增高时,更会使这些合金的热加工和冷加工发生困难。一般应使合金中碳含量小于碳在该合金中的溶解度0 .03一0 .033男;为了改善这类合金的加工性能,添加0.1一0.5终稀土元素是比较有效的;加入0.1一1.0终Y在Fe一C卜Al合金中对抗氧化性有显著提高,并对加工性能有良好的影响;其它Ti、Zr、Be、Mg、Ba等元素也均有不同程度的改善作用。为了探讨铝、钒、忆和稀土元素对合金加工性的影响,我们采用正交设计方案研究了合金元素对抗拉强度和延伸率的影响,提供了通过添加元素改进合金加工性能的重要依据。在工艺上对合金的"纯度"、浇注工艺和热加工工艺采取了改进措施。为了解决冷拉丝材的困难,我们还采用了温拉工艺。温拉加热温度为200~300℃,这是由于在此温度时可以得到较高的塑性而又不致于使合金的强度降低很多,以保证合金在拉丝过程中具备必要的抗拉伸变形的强度。     

耐低温冲击高强高韧合金的组织与性能

高强高韧合金铸钢具有优良的力学和物理化学性能,使得其具有巨大的发展潜力和经济效益。通过合理的成分设计及热处理工艺,获得制备工艺简单、强韧性高、成本低、污染小,且具有良好低温韧性、焊接性的低合金已成为一项技术问题。本工作针对奥氏体-马氏体高耐蚀高强度合金,通过成分与热处理的良好匹配,使合金达到优良的强塑性。对合金组织和性能进行分析,得出影响合金力学性能的主要因素,为大批量制备该合金打下坚实的基础。通过试验结果可知:相同回火温度下,随着碳含量的增加,合金的室温拉伸强度升高,塑性下降;相同碳含量下,回火温度从480℃升高到540℃,室温拉伸强度先升高后降低,在520℃下达到峰值1 552 MPa,冲击韧性先升高后降低,在500℃时达到最大值54 J·cm~(-2)。合金热处理冷却方式由空冷调整为油冷后,其强度和塑性大幅提高,室温拉伸强度达到1 580 MPa,冲击韧性达到100.6 J·cm~(-2)。     

碳含量对高合金铁基材料组织与性能的影响

研究了高合金铁基材料中碳含量对材料显微组织与性能的影响.采用光学显微镜、扫描电镜和能谱分析表明:碳含量对材料烧结密度和性能影响显著.热处理后,材料硬度上升,但强度和韧性下降.烧结时,碳含量增加,使液相量增加,晶界上的液相膜增厚,晶粒球化;碳化物大部分在晶界上析出,形成半连续网络组织.热处理后,由于部分碳化物的溶解,一些连续的网络组织断裂.实验得出,1250±5.°C烧结,碳含量为1.4%时,烧结致密化程度最高,相对密度达到96%,各项性能也达到最高.本实验通过合理控制碳含量,获得了高性能的铁基粉末冶金材料.     

Effects of carbon and chromium on the solidification structure and properties of ferrite-austenite duplex heat-resistant alloy

In order to design a new kind of low-cost high-temperature ferrite-austenite duplex alloy, the effects of carbon and chromium on the alloy solidification structure and properties have been investigated with orthogonal experiments. The addition of carbon promotes strongly the formation of austenite and that of carbides in the alloy solidification structure and refines the alloy grains. With the increase of carbon content, the alloy high temperature strength and oxidation resistance at 1250°C improves at first, but then begins to deteriorate greatly when the carbon content exceeds 0.15%. The addition of chromium facilitates the formation of ferrite in the alloy solidification structure. As the chromium content increases, the alloy rupture strength at 1250°C initially is enhanced, but then reduces rapidly, while the alloy oxidation resistance improves continuously.     

Effects of carbon content of carbon steel on its dissolution into a molten aluminum alloy

Hot dip aluminizing of carbon steels with different carbon concentration ranging 0.2–1.1 wt.% was carried out in a molten Al–9.08 wt.% Si–0.98 wt.% Fe alloy at 660 °C. The steel specimens lost weight as a result of dissolution into the melt, and an intermetallic layer was formed on the surface of them. The specimens showed varied dissolution rates depending on carbon concentration. The specimen with the highest carbon content exhibited the slowest dissolution rate. The thickness of the intermetallic layer increased with dipping time following a parabolic relationship. The growth rate of the layer decreased with increase of the carbon content. A diffusion mechanism to control the dissolution of the carbon steel into the molten aluminum alloy was suggested, and the effect of carbon content on the dissolution of the steel substrate into the melt was discussed in connection with the proposed diffusion mechanism and microstructural observations.     

Effects of carbon and chromium on the solidification structure and properties of ferrite–austenite duplex heat-resistant alloy

In order to design a new kind of low-cost high-temperature ferrite–austenite duplex alloy, the effects of carbon and chromium on the alloy solidification structure and properties have been investigated with orthogonal experiments. The addition of carbon promotes strongly the formation of austenite and that of carbides in the alloy solidification structure and refines the alloy grains. With the increase of carbon content, the alloy high temperature strength and oxidation resistance at 1250°C improves at first, but then begins to deteriorate greatly when the carbon content exceeds 0.15%. The addition of chromium facilitates the formation of ferrite in the alloy solidification structure. As the chromium content increases, the alloy rupture strength at 1250°C initially is enhanced, but then reduces rapidly, while the alloy oxidation resistance improves continuously.     

Carbon additive effects on the nanostructure and magnetic property of the Co-Fe-Zr-B-C films

In this study, the carbon additive Co-Fe-Zr-B alloy films were prepared by dual-gun co-sputtering. The effects of the carbon addition and heat treatment on the nanostructure and magnetic properties of the Co-Fe-Zr-B-C alloy films are reported. The experimental results show that a crystalline (Co, Fe) phase formed after heat treatment at 400 in the Co-Fe-Zr-B-C films with low carbon additive level. Carbon atoms inhibited the crystallization of the as-deposited Co-Fe-Zr-B-C films. From the TEM observation, the nanostructures, such as the atomic structure and grain sizes, showed a strong carbon content dependence. The coercivities of the Co-Fe-Zr-B-C films annealed at 400 varied from 18 to 0.3 Oe with the increasing carbon addition. However, the films annealed at higher temperature exhibited a dramatic increase in the coercivities, which correlated to the formation of the crystalline (Co, Fe) phase. The resistivities of the Co-Fe-Zr-B-C films relied on the carbon contents rather than on annealing temperatures.     

氢对TC21钛合金热物理性能的影响

目的 获得氢含量对TC21钛合金密度、热扩散系数、比热容和热导率等热物理性能的影响规律.方法 利用固态置氢法对TC21钛合金进行氢处理,利用固体密度测试仪、激光导热仪和差示扫描量热仪等设备测定原始及含有不同氢含量TC21钛合金的热物理性能.结果 随着氢含量的增加,TC21钛合金的密度呈线性降低趋势;TC21钛合金在不同...     

Wear and mechanical properties of carbon fiber reinforced copper alloy composites

The mechanical properties and wear behavior of lead-free metal matrix composite, and carbon fiber reinforced copper alloy composites were studied, and compared with a common leaded copper (Cu-6wt.%Zn-6wt.%Sn-3 wt.%Pb) alloy. The effects of carbon fibers and alloy element Sn on these properties were investigated. Carbon fiber/Cu–Sn–Zn composites showed higher hardness and bending strength than the leaded copper alloy when carbon fibers content is less than 12 vol.%. Tribological tests were conducted with disks made from these materials, and tested against a steel counterface. The carbon fiber/Cu–Sn–Zn composites showed higher wear resistance than the leaded copper alloy under a constant load of 50 N. Observations on surface morphology were utilized in understanding the wear properties of these materials. The results show that the wear mechanism of the leaded copper alloy is adhesive wear, while it is mainly adhesive wear accompanied by oxidative wear for the 12 vol.% carbon fiber/Cu–Sn–Zn composites. The 12 vol.% carbon fiber/Cu–Sn–Zn composites are likely to provide optimum substitutes for the leaded copper alloy under the load of 50 N.     

Influence of alloying on hydrogen-assisted cracking and diffusible hydrogen content in Cr-Mo steel welds

Study of hydrogen-assisted cracking and measurement of diffusible hydrogen content in different Cr-Mo steel welds shows that under identical conditions, susceptibility to cracking increased and diffusible hydrogen content decrease with increase in alloy content. Hydrogen permeation studies show that hydrogen diffusivity decreases and solubility increases with increase in alloy content. Thus decrease in diffusible hydrogen content with increase in alloying is attributed to increase in apparent solubility and decrease in apparent diffusivity of hydrogen. Analysis of the results indicates that variation of diffusible hydrogen content and apparent diffusivity of hydrogen with alloy content can be represented as a function of carbon equivalent CE₁ originally proposed to predict the hardness in the heat-affected zone of alloy steel welds.     

Evidence for Cr-carbide formation at the scale/metal interface during oxidation of FeCrAl alloys

Two FeCrAlY alloys with different carbon contents (90 and 500 ppm, respectively) were investigated in respect of their oxidation behaviour at 1200 °C in air. Both alloys exhibited formation of grain boundary Cr-carbides after 1200 °C exposure, whereas the high-carbon content alloy additionally showed carbide formation at the interface between alloy and alumina surface scale. The extent of the carbides formed at both this interface and the alloy grain boundaries was dependent on the cooling rates of the oxidized samples. The presence of the carbides may decrease the adherence of the oxide scale to the metallic substrate and explain the decreased time to breakaway oxidation of the high-carbon content alloy.     

Effects of carbon and titanium on the solidification structure and propertiesof ferrite heat-resistant alloy

In order to design a low-cost high temperature ferrite alloy, the effects of carbon, and titanium on its solidification structure and properties have been studied. When the carbon content is increased from 0.07 to 0.35 wt%, the alloy grains becomes finer, and the grain boundaries become wider and more zigzag. The alloy oxidation weight-gain rate at 1300°C keeps increasing clearly, however, that at 1350°C decreases at first then increases. When the carbon content is above 0.15 wt% the alloy strength at 1300°C decreases acutely. When the titanium content increased from 0.30 to 0.60 wt%, the alloy grains became fine, and both the alloy strength and oxidation resistance improved remarkably.     

Synthesis and properties of carbons dispersed with Fe-Co alloy by pressure pyrolysis of organoiron-organocobalt copolymer

Carbons dispersed with Fe-Co alloy were synthesized by the pressure pyrolysis of vinylferro cene-phenylethynylcobaltocene-divinylbenzene copolymer at temperatures below 700° C and at 125 M Pa. As-prepared carbon synthesized at 550° C contained finely dispersed metallic particles of less than 10nm diameter with low crystallinity, which crystallized to form Fe-Co alloy particles with a higher crystallinity by subsequent heat treatment at 800° C. Larger particles of the alloy of more than 50nm diameter were dispersed in the carbon matrix synthesized at 700° C. Thermomagnetization measurement of the as-prepared carbon synthesized from divinylbenzene-2.1 mol% vinylferrocene-4.8mol% phenylethynylcobaltocene copolymer at 550° C and 125 M Pa confirmed that iron formed an alloy with cobalt in the carbon matrix. Fine, superparamagnetic metallic particles in the as-prepared carbon aggregated and crystallized by the heat treatment during the thermomagnetic measurement to increase the magnetization of the alloy-dispersed carbon. The saturation magnetization and the coercive force of alloy-dispersed carbon increased from 128 to 187e.m.u.g^–1 and from a few to 50 Oe, respectively, on increasing the pyrolysis temperature of the starting copolymer from 550 to 700° C. The saturation magnetization of alloy-dispersed carbon from divinylbenzene containing iron and cobalt with a ratio of 52 was higher than that from divinylbenzene including those with a ratio of 25. The carbon with finely dispersed Fe-Co alloy showed a high saturation magnetization of 213 e.m.u.g^–1 and a coercive force of 230 Oe, and the magnetization persisted above 800° C.