共查询到19条相似文献,搜索用时 140 毫秒
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激光熔覆TiC/Ni+Cr涂层过程中陶瓷相的行为 总被引:1,自引:0,他引:1
借助SEM,TEM对激光熔覆TiC/Ni+Cr过程中陶瓷相TiC的行为进行了研究。结果表明:未受基体中Fe扩散影响的熔覆层表层,TiC仍保持为完整的六边形截面颗粒。交互扩散区的TiC颗粒在凝固应力作用下可能产生裂纹。 相似文献
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激光熔覆Fe—Ti—B复相涂层的组织研究 总被引:3,自引:1,他引:2
应用5kW激光器在1Cr18Ni9Ni不锈钢基体上进行Fe-Ti-B合金的激光熔覆,用金相显微镜、X射线衍射、电子探针等微观分析手段对涂层中组成相的 类型和形貌进行了分析。结果发现涂层中TiB2有针状、棒状以及颗粒状等形状。这与激光加工工艺参数有关,同时由于TiB2的生成消除了激光熔覆Fe-B合金涂层中Fe-B相的偏析。 相似文献
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研究了Ce对AlCuFeCr准晶合金凝固特性的影响。结果表明加入Ce能提高AlCuFeCr合金的硬度,加入适量的Ce可细化晶粒;而且固液界面的生长方式随着Ce含量的增加而明显改变,使合金凝固形貌表现出由胞状晶向胞状枝晶再向树枝晶转变的规律 相似文献
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Ti是极有效的细化晶粒元素,随Ti含量增加,合金由粗大柱状晶变为细小等轴晶;合金的室温、高温抗拉强度随Ti含量增加而高,在0.55%Ti时达到峰值,Ti是提高该合金抗氧化性的有效元素;Fe-Cr-Al合口中适宜的Ti含量为0.4~0.7%。 相似文献
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研究了快速凝固Al-Fe-Ti-C合金的显微结构及退火过程中的相变。初始快凝态组织由α-Al微胞晶组成,在胞晶边界分布着较大并拉长的非晶相;在胞晶内部则为细小弥散的球状亚稳Al_6Re相(底心正交结构),Ti和C全部过饱和固溶于α-Al中。当773K退火5h时,非晶相转变为α_T-AlFeSi相(斜方结构),Al_6Fe相部分转变为片状Al_3Fe相(底心单斜结构),部分长大但仍保持球状和底心正方结构过饱和固溶于α-Al基体中的Ti和C则以TiC形式弥散析出。 相似文献
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研究了快速凝固Al-Fe-Ti-C合金的显微结构及退火过程中的相变。初始快凝态组织由α-Al微胞晶组成,在胞晶边界分布着较大并拉长的非晶相;在胞晶内部则为细小弥散的球状亚稳Al_6Re相(底心正交结构),Ti和C全部过饱和固溶于α-Al中。当773K退火5h时,非晶相转变为α_T-AlFeSi相(斜方结构),Al_6Fe相部分转变为片状Al_3Fe相(底心单斜结构),部分长大但仍保持球状和底心正方结构过饱和固溶于α-Al基体中的Ti和C则以TiC形式弥散析出。 相似文献
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采用Ni-Cr、Ag-Cu-Ti和Ti-Zr-Ni-Cu等钎料分别对单晶金刚石与基体进行真空钎焊。SEM、EDS和XRD等分析结果表明,在一定的钎焊温度、时间及真空度下,金刚石与所有钎料均形成化学冶金结合,在不同钎料界面形成的碳化物的种类、数量和形貌分布却显著不同;Ni-Cr合金钎料在界面处形成片状的Cr3C2和针状Cr7C3;Ag-Cu-Ti钎料则生成不连续分布块状TiC,Ti-Zr-Ni-Cu生成的是呈鹅卵石状连续分布的TiC。 相似文献
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A. E. Karantzalis A. Lekatou M. Evaggelidou 《International Journal of Cast Metals Research》2014,27(2):73-79
Monolithic Co and Co based composites reinforced by TiC precipitates were fabricated by vacuum arc melting process. The ratio of hexagonal to cubic phase cobalt was affected by the presence of the TiC precipitates. The microstructure of the produced materials was also associated with the presence of TiC crystals. The TiC primary precipitates are characterised by a strong faceted morphology which is explained in terms of Jackson’s theory of crystal growth. The solidification progress was altered by the presence of the TiC crystals. The sliding wear behaviour of the produced composites was assessed in terms of wear track and debris examination and compared to that of Co29Cr5Mo alloy. 相似文献
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将Fe-Cr-Ti-C系耐磨药芯焊丝采用钨极氩弧焊堆焊到低碳钢表面,分析熔覆层中的物相组成,研究熔覆层中硬质相的形态分布和生长机理,探究熔覆层的耐磨性及表面硬度等力学性能变化的原因. 结果表明,药芯堆焊焊丝中的合金元素的过渡系数很高,可原位合成(Fe,Cr)7C3和TiC硬质相,TiC优先依附外来界面行核、长大,共晶(Fe,Cr)7C3硬质相则依附于初生马氏体相和TiC形核生长,点状TiC硬质相(少数为条状和十字状)弥散分布于马氏体、残余奥氏体的基体中,与网状的(Fe,Cr)7C3耐磨框架组成复合硬质相,提高熔覆层的耐磨性. 相似文献
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目的 在钛合金表面制备陶瓷相增强复合耐磨涂层。方法 采用等离子弧熔覆技术,在Ti6Al4V钛合金表面制备了原位自生TiB2、TiC、CrB陶瓷相增强镍基耐磨涂层。采用X射线衍射仪、扫描电镜、能谱仪检测了涂层的物相组成、组织组织以及微区化学成分,采用显微硬度计测试了涂层的硬度。结果 涂层靠近熔合线区域由Ni-Ti树枝晶及枝晶间的共晶组成,在涂层的中上部,大量原位增强相分布于镍基固溶体基体之中。在熔覆过程中,钛合金基材中的Ti元素同熔覆粉末中的B、C元素发生原位冶金反应形成TiB2、TiC增强相,CrB增强相为Ni基熔覆粉末中Cr、B元素反应形成,增强相的形态由各自的晶体结构及熔池凝固热力学与动力学条件决定。涂层的显微硬度得到显著提高,最高达1037HV0.2。结论 采用等离子弧熔覆技术,利用熔池内Ni-Cr-Ti-B-C合金体系的原位冶金反应,可以在钛合金表面制备原位自生TiB2、TiC、CrB增强镍基复合耐磨涂层。同Ti6Al4V基材相比,由于涂层具有大量增强相分布于镍基固溶体的组织特征,其显微硬度得到了显著提高。 相似文献
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Interface microstructure and formation mechanism of diffusion-bonded joints of TiAl to steel 40Cr 总被引:3,自引:2,他引:3
1 INTRODUCTIONInrecentyears,considerableinteresthasbeengiv entoTiAlintermetallicsbecauseofitsuniquepropertiessuchaslowdensity ,goo 相似文献
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自生TiCp/Ti复合材料中TiC的生长习性 总被引:5,自引:0,他引:5
利用配位多面体生长基元理论研究了自生TiCp/Ti复合材料中TiC的生长习性。TiC晶体的配位多面体生长基元为TiC6。生长基元进入{100}面时为4个棱边同时联结,生长速率最快,不易显露;进入{111}面时为共面联结,生长速率最慢,容易显露。因此,TiC晶体的理想形态为{111} 面为显露面的八面体。TiC晶胚在熔体中生长时,受传热传质过程的影响,6个顶角所处的{100}方向生长速率加快,形态失稳,从{100}方向顶角部位生长出二次枝晶臂,最终形成棱面枝晶状TiC。如枝晶形成时低生长速度的晶面上形成大量的晶体缺陷,则它们的生长速度加快,棱面消失,成为光滑枝晶。 相似文献
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Ni-Cr weld overlay alloys with dispersed carbide particles were prepared by a plasma transferred arc welding process. The
corrosion behavior of the 40 vol% carbide/Ni-Cr materials was studied in sodium chloride solution by electrochemical techniques,
scanning electron microscopy, x-ray diffraction, and electron dispersive spectroscopy. The materials under investigation were
powder blends of Ni-50 mass % Cr powder mixed with NbC, TaC, TiC, WC, O3C2, or VC. The NbC, TaC, TiC, and WC particles partially dissolved in the molten alloy, causing the crystallization of M23C6. Blends with Cr3C2 and VC particles produced the crystallization of M7C3, VxCryCz and M23C6. The VC/Ni-Cr alloy combination caused preferential localized corrosion and the carbide remained as VxCryCz. The Cr3C2/Ni-Cr alloy combination became studded with the Cr-Cl corrosion product compound. With the WC/Ni-Cr alloy combination, the
WC particles became oxidized and corrosion product spread over the matrix. Other carbides were not oxidized, but the matrix
of the alloys with these dispersed particles did become covered with Cr-rich corrosion products. The NbC/Ni-Cr material exhibited
the best corrosion resistance. 相似文献
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The structural energy difference between stable bcc and metastable fcc structures of Cr are investigated via a detailed first-principles
and phenomenological study of the thermodynamic properties of Ni-Cr alloys. Our work focuses on the large discrepancies between
the first-principles calculations of structural energies and those obtained from phase diagram studies. For the Ni-Cr system,
we find that the existing phase diagram and thermochemical data are insufficient to assess accurately the structural energies
of Cr. Electronic structure calculations based on a tight-binding (TB) approximation for the alloy Hamiltonian are used, together
with available thermochemical data, to obtain more reliable estimates of structural energies.
This research was funded by the National Science Foundation under grant No. DMR 85-10594. 相似文献