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本文采用X射线衍射分析、SEM、TEM及显微金相组织观察等综合分析手段,主要研究了稀土金属La、Ce及混合稀土RE添加到普通工业导电纯铝中对其(室温和高温下)导电性能、力学微观铸态组织的影响。探讨了稀土地其中的作用机理,发现加入稀土元素La、Ce后明显细化了纯铝的晶粒及枝晶间距,并使名中有害杂质元素Fe、Si由因溶态转变为析出态,在晶界处以铝稀土和铁硅等的多元金属间化合物相存在,从而改善了铁硅的有 相似文献
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氟碳铈矿热分解行为的研究 总被引:10,自引:0,他引:10
采用XRD法分析了不同温度下氟碳铈矿焙烧分解产物的组成,探讨了氟碳铈矿的热分解过程。试验结果表明氟碳铈矿的热分解是分步进行的。首先(Ce,La)CO3F分解成(Ce,La)OF;升高焙烧温度,(Ce,La)OF发生相分解,生成Ce0.75Nd0.25O1.875和(Ce,Pr)La2O3F3两相;随着焙烧温度的继续升高,(Ce,Pr)La2O3F3可分解为LaF3、Ce2O3、PrO1.83等相。焙烧过程中Ce3+、Pr3+氧化为四价,没有明显的脱氟行为。 相似文献
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西南稀土矿的矿石性质及分选工艺研究 总被引:2,自引:0,他引:2
研究了西南稀土矿的矿石性质及分选工艺.原矿风化强烈,产生大约20%的黑色风化物矿泥。-矿石中可工业利用的稀土赋存形式有矿物相和胶态相。矿物相稀土以氟碳铈矿为主,占96%以上,重选或重浮选联合工艺可得到REO30%,50%和60%的氟碳铈矿精矿,稀土回收率65%。胶态相稀土则吸附在Fe-Mn非晶质氧化物矿物上,用热盐酸浸出,氨水除杂,草酸沉淀回收稀土,稀土回收率74.3%,并副产铅。矿石和黑色风化物中稀土都强烈选择铈族稀土,∑CeO2在90%以上,且CeO2>La2O3>Nd2O3。 相似文献
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用金相、透射电子显微镜、电子探针与扫描电镜分析研究得出超低碳Cr26-Ni28-Mo5-Cu3-Nb0.35不锈钢铸态组织中含有σ相,经850 ̄1120℃热处理均可形成σ相,包括(Fe-Cr)σ相,(Fe-Mo)σ相和(Cr-Ni-Si)σ相,850℃左右有M6C型碳化物和NbC析出。该钢经1150℃2h水冷固溶处理后,具有优良的耐腐蚀性能。 相似文献
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本文主要研究PrFeB及其加Cu、Nb、Zn四种铸造合金的铸态结晶组织和其磁性,结果表明:PrFeB系铸造合金中加入Cu、Nb、Zn或提高Pr含量没有改变这种铸态合金磁性能的磁各向异性,证实了PrFeB系铸造合金具有的磁各向同性特征与合金的凝固形式和结晶方向无关。 相似文献
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通过硬度测试、金相显微镜(OM)、扫描电镜(SEM)、X射线衍射物相分析(XRD)、均匀腐蚀和电化学腐蚀实验以及微动摩擦实验等分析手段,研究了锆微合金化铸态镍铝青铜的硬度、组织、均匀腐蚀性能、电化学腐蚀性能和摩擦磨损性能。结果表明:与未微合金化铸态镍铝青铜(Cu-8.87Al-5.22Fe-4.48Ni-1.08Mn-0.53Zn)相比,锆微合金化铸态镍铝青铜(Cu-9.92Al-5.24Fe-4.43Ni-1.07 Mn-0.52Zn-0.045Zr)的相组成没有显著变化,都由α相、β相(高温相)和κ相(包括κI,κII,κIII和κIV)组成,但α相、κIII相和κIV相显著细化。锆微合金化铸态镍铝青铜的硬度由HV212.1提高到HV229.3,比未微合金化铸态镍铝青铜高8.1%,晶粒细化且呈弥散分布是硬度提高的主要原因。由于腐蚀优先发生在共析区域(α+κIII相)内,组织细化降低了该区域腐蚀长通道产生的概率,使得锆微合金化铸态镍铝青铜在3.5%NaCl水溶液中的均匀腐蚀速率和电化学腐蚀速率分别降低到0.022954754和0.26193 mm·a-1(分别降低了5.3%和8.45%);硬度提高、组织细化以及位错强化作用使得锆微合金化铸态镍铝青铜的摩擦系数降低到0.022(降低了12.7%)。 相似文献
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Kondrat’ev Sergey Yu. Anastasiadi Grigoriy P. Petrov Sergey N. Ptashnik Alina V. 《Metallurgical and Materials Transactions A》2017,48(1):482-492
Metallurgical and Materials Transactions A - The kinetics of formation and morphology of the intermetallic phases in the structure of heat-resistant as-cast HP40NbTi alloys in the course of long... 相似文献
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Vibratory cavitation erosion tests were carried out on as-cast NiAl intermetallic compounds containing 46.5 to 62.1 at pct
Ni. The erosion rate decreased with increasing nickel content by over two orders of magnitude, from a high of 16.4 to 0.11
mg·h−1. These low erosion rates exhibited by the nickel-rich alloys containing 58 and 62.1 at. pct Ni, the interruptions in their
mass loss with time, and the unusual effects associated with surface finish and intensity of cavitation were found to be associated
with the stress-induced martensitic transformation. Alloys containing 58 to 62 at. pct Ni have the potential for use as materials
for the cavitation protection of hydraulic machinery. 相似文献
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Lipika Rani Bairi G. Pannerselvam U. Kamachi Mudali 《Transactions of the Indian Institute of Metals》2012,65(4):333-341
Zirconium present in stainless steel-zirconium metal waste form (MWF) alloys form Ni?CZr and Fe?CZr intermetallic phases which act as a sink for radionuclide and improve resistance to localized corrosion as well as selective radionuclide leaching. The present study looks into the behavior of Zr intermetallics in MWF alloys with the variation of Zr content after heat treatments. Two MWF alloys of D9 SS (Ti modified 15Cr?C15Ni?C2.5Mo stainless steel) with 8.5 and 17?wt% Zr were heat treated at 1,323?K for 2 and 5?h and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The stability of the Zr intermetallic compounds was examined by high temperature XRD. The results from XRD study showed the presence of NiZr, Ni5Zr, Ni7Zr2, FeZr2, and Fe3Zr peaks along with fcc Fe based solid solution. The MWF alloy with 17?wt% Zr exhibited ??-ferrite peak in as-cast condition which was not observed after heat treatment. From the SEM micrograph the agglomeration of intermetallic phases was observed after heat treatment and the grain size of the intermetallic phases increased with duration of heat treatment. The high temperature XRD study revealed that all the intermetallic phases were stable up to 1,173?K and above this temperature Ni?CZr intermetallics started disappearing. However Fe?CZr intermetallics were stable till 1,373?K. The paper presents the high temperature phase stability of D9 SS-Zr MWF alloys. 相似文献
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L. I. Kivalo V. V. Pet'kov A. V. Polenur V. V. Skorokhod 《Powder Metallurgy and Metal Ceramics》1988,27(4):279-283
Conclusions The temperatures of accelerated formation of intermetallic compounds in the Ti-Fe-Mn system correspond to the temperatures of sharp changes in the direction and rate of the sintering process and also of the appearance of heat evolution peaks. The rate of heating of compacts to sintering temperatures affects the mechanism of formation of intermetallic compounds: At lower rates of heating intermetallic compounds are formed by solid-phase reaction, while at higher rates the role of liquid phase grows. A relation has been established between the composition of the intermetallic compounds forming during sintering and the behavior of specimens during this process at various heating rates. At higher rates of heating of Ti-Fe-Mn compacts Ti-Fe intermetallic compounds are formed containing no Mn; the behavior of these specimens during sintering is similar to that of Ti-Fe compacts (the specimens grow). At lower heating rates intermetallic compounds alloyed with Mn are formed, and growth of specimens is followed by their shrinkage.Translated from Poroshkovaya Metallurgiya, No. 4(304), pp. 23–28, April, 1988. 相似文献
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Hiroki Adachi Wataru Itaka Tetsuo Aida K. Osamura Manabu Imaoka Jun Kusui 《Transactions of the Indian Institute of Metals》2009,62(2):163-167
Heat-resistant aluminum alloys are generally developed by dispersing stable intermetallic compounds by adding transition metals
(TM) whose diffusion coefficient in aluminum alloys is low even at high temperatures. Commonly used intermetallic compounds
include Al-TM binary intermetallic compounds, for example, Al6Fe, Al3Ti and Al3Ni. By contrast, multicomponent intermetallic compounds are hardly used. The present study focuses on Al-Mn-Cu and Al-Mn-Ni
ternary intermetallic compounds, and by finely dispersing these intermetallic compounds, attempts to develop heat-resistant
alloys. Through the atomization method, Al-(4.96–5.96)Mn-(6.82–7.53)Cu-0.4Zr and Al-(5.48–8.76)Mn-(2.23–4.32)Ni-0.4Zr (in
mass%) powders were fabricated, and by degassing these powders at 773 K, intermetallic compounds were precipitated. These
powders were then solidified into extrudates by hot extrusion at 773 K. The microstructural characterization of powders and
exrudates was carried out by XRD analysis, SEM/EDX and TEM. The mechanical properties of extrudates were determined at room
temperature, 523 K and 573 K. In Al-Mn-Cu alloys, while a small amount of Al2Cu was crystallized, precipitated Al20Mn3Cu2 intermetallic compounds were mainly dispersed. In Al-Mn-Ni alloys, while a small amount of Al6Mn intermetallic compounds was precipitated, the precipitated A60Mn11Ni4 intermetallic compounds were mainly dispersed. Both ternary intermetallic compounds were about 200 nm in size. The compounds
were elliptical, and their longitudinal direction was oriented along the extrusion direction. In the Al-Mn-Cu alloys, since
the work hardening at room temperature was high, the tensile strength became 569 MPa. At elevated temperatures, since hardly
any work hardening was observed, the tensile strength decreased markedly. However, in Al-Mn-Ni alloys, since the work hardening
is low even at room temperature, the roomtemperature strength is not high. Thus, the decrease in tensile strength at elevated
temperatures is relatively small and a high strength was obtained at 523 K and 573 K: 276 MPa and 207 MPa, respectively. 相似文献
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《中国稀土学报(英文版)》2017,(12)
The microstructures and mechanical properties of a series of sand-cast Mg-Sm-Zn-Zr alloys under ascast, solution-treated and peak-aged states were thoroughly investigated. The OM, XRD, SEM and HRTEM were employed to characterize the microstructural evolution. The results indicate that substitution Nd in the conventional Mg-2.5 Nd-0.6 Zn-0.5 Zr alloy with different contents of Sm has comparative grain refinement effect and will fully change the dominant intermetallic phase. In addition, the substituted alloys perform clearly higher strength with comparative ductility at both as-cast and peakaged conditions and much greater aging hardening response than the referential alloy. It is obvious that the strength increments of this alloy are attributed to the changes of the eutectic intermetallic particles on grain boundaries. 相似文献
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Au/Sn界面互扩散特征 总被引:3,自引:2,他引:3
从扩散机制、扩散动力学、热力学以及相结构等方面,总结了室温范围内Au/Sn互扩散的主要特点。给出了Au/Sn互扩散中生成的AuSn,AuSn2,AuSn4等金属间化合物的主要性质。详细总结了不同Sn含量的Au/Sn扩散中,初始态、中间态和最终态的金属间化合物的形成次序、形貌、分布、演化等特征。采用热力学方法定量计算了不足量的Au或Sn的条件下Au/Sn扩散中各中间相的生成吉布斯自由能,较好地解释了中间相的演化规律。给出了Au/Sn扩散的扩散数据,以及主要中间相的生长特点,介绍了Kirkendall效应导致的相关效应。 相似文献
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V. V. Cheverikin A. V. Khvan V. S. Zolotorevskiy V. S. Levchenko T. Ernandes Lara 《Russian Journal of Non-Ferrous Metals》2011,52(6):490-495
Fragments of the Al-Zn-Mg + (Ni, Fe, Mn, Cr) phase diagrams are analyzed using both experimental techniques and calculation
with the ThermoCalc software package. The structures of ternary eutectics are analyzed in the as-cast and annealed states.
Alloy compositions with a high content of disperse eutectics forming at a moderate cooling rate are found. The intermetallic
phases in eutectics are shown to be fragmented and spheroidized during homogenizing annealing before quenching. 相似文献
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Ti57−x
Cu15Ni14Sn4+x
Nb10 (x = 0, 5, or 10) alloys were prepared by copper mold casting. At Sn = 4 at. pct, a dendrite/ultrafine-structured multicomponent
alloy was obtained, which exhibits 1271 MPa yield strength, 77 GPa Young’s modulus, and 2 pct plasticity at room temperature
for 3-mm-diameter samples. The cooling rate significantly affects the as-cast microstructure and the mechanical properties.
For 5-mm-diameter samples, the alloy exhibits 1226 MPa yield strength, 63 GPa Young’s modulus, and 2.5 pct plasticity. At
Sn = 9 at. pct, Ti-, Sn-, and Nb-rich particles precipitate primarily. This near-hypereutectic alloy composition leads to
the precipitation of intermetallics, which deteriorate the mechanical properties and result in the coexistence of ductile
and brittle fracture mechanisms. At Sn = 14 at. pct, the alloy composition is completely in the intermetallic region, thus
inducing the formation of Ti2Cu, Ti2Ni, and Ti3Sn intermetallics. The alloy becomes very brittle because the intermetallic compounds dominate the fracture process. 相似文献