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1.
It was with great interest that the article published by Mita et al. [1] was studied. In the article, experimental measurements of vapor pressures of various Zn-Fe intermetallic compounds were reported. Zinc activities were derived from the vapor pressure measurements. Such thermodynamic data, albeit indispensable for phase diagram construction, are scarce and often outdated as many researchers today opt to work on computation over experimentation for quick results. Data on zinc-related systems are even scarcer in comparison to other common metals such as iron, aluminum, or copper. It is certainly encouraging to see this experimental work on the Zn-Fe system.  相似文献   

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以Al和Mg元素混合粉末为原料,用粉末冶金模压成形和无压反应烧结方法制备出Al-Mg金属间化合物多孔材料,研究反应过程中Al-Mg金属间化合物多孔材料的相转变、体积膨胀、孔结构参数和显微形貌的变化,并对其孔隙形成机理进行讨论。研究结果表明:烧结后Al-Mg金属间化合物形成了均一的Al3Mg2相并发生了显著的体积膨胀,开孔隙率随温度的升高而增大,经435℃烧结后,达到24.7%;造孔机理是压制过程中粉末颗粒间隙孔的产生和固相扩散过程中的Kirkendall效应造孔。  相似文献   

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Ni-Al金属间化合物多孔材料的制备   总被引:1,自引:0,他引:1  
以Ni、Al元素混合粉末为原料,用冷压成形和两阶段固态偏扩散反应烧结法制备Ni-Al金属间化合物多孔材料,系统地研究合金成分、Al粉粒度和烧结温度对孔结构的影响.研究结果表明:随着铝含量增加开孔隙率先缓慢增大而后迅速增大,最大孔径和透气度也随铝含量的增加而增大,开孔隙度则随温度升高增大到一定值后呈减小趋势;随着Al粉粒度增大,最大孔径和透气度都增加,透气度的增加趋势更为显著.  相似文献   

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The formation heats of the intermetallic compounds of aluminum and cerium were studied using a differential direct isoperibol calorimeter. The composition and equilibrium state of the samples were confirmed by metallographic and X-ray analyses. For the various compounds, the ΔHform (for the reaction in the solid state at 300 K) was determined as follows (kJ/mol of atoms): Ce3Al: -27.0 ± 2; CeAl: -46.0 ± 3; CeAl2: -50.0 ± 2; and Ce3Al11: -41.0 ± 2. The results are discussed and compared with the values which can be found in literature.  相似文献   

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Mechanical properties of high-temperature titanium intermetallic compounds   总被引:1,自引:0,他引:1  
A suite of 36 alloys has been tested that is based on titanium-containing ordered intermetallic compounds. Microhardness and tendency toward formation of cracks are reported as a function of temperature; room-temperature Young’s moduli are summarized; and results of simple roomtemperature toughness tests are given. Using toughness, low specific gravity, and hardness at 1000 °C as figures of merit, Ti-Cr-Nb alloys are recognized as deserving of more intense study. Certain Ti-Sn-Al and Ti-Re compositions may also be of continuing interest.  相似文献   

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Aligned nickel wire bundles 4 to 5 cm in length and up to 2.5 cm in diameter are infiltrated by pure aluminum using gas-assisted infiltration, to produce samples having global compositions in the range of 40 to 76 at. pct nickel. As-reacted sample macrostructures feature a large single-phase region of NiAl independent of applied pressure and nickel preform volume fractions in the ranges of 0.15 to 0.3 MPa and 0.23 to 0.44, respectively. These macrostructures also contain, in some cases, either an aluminum-rich zone on top, or nickel-rich phases at the bottom of the sample, depending on the global stoichiometry of the material. Two high-speed digital cameras are used to record the infiltration and reaction processes. The acquired images show that infiltration and reaction are decoupled in time. Infiltration proceeds initially under partial preform saturation, at a rate on the order of 50 cm·s−1. The sample then self-heats for 2 to 3 seconds due to exothermic reaction between aluminum and nickel. Thereafter, a spontaneous combustion front ignites due to local melting of nickel and propagates at an average rate on the order of 5 cm·s−1. Macrostructures and process kinetics are explained by the combined influences of capillarity during infiltration, heat evolved during the reaction, and gravity.  相似文献   

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Ternary intermetallic compounds in the system Ni-Ti-Nb   总被引:1,自引:0,他引:1  
Conclusions Four ternary intermetallic compounds -Ni80Ti5Nb15, Ni75Nb5Ti20, Ni75Nb13Ti12 and Ni56Ti29Nb15 -were dis-covered in the system Ni-Ti-Nb by the methods of x-ray diffraction analysis. Isothermal phase diagram sections at 1000 and 900C have been plotted.Translated from Poroshkovaya Metallurgiya, No. 8(44), pp. 61–69, August, 1966.  相似文献   

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Mössbauer spectra were obtained for α and β-Al-Fe-Si intermetallic compounds, which are usually detected as precipitates in commercial grade Al metals. The samples were prepared by two methods, electrolytic extraction of precipitates from Al ingots and direct melting of appropriate amounts of raw materials. By the latter method, pure compounds have been obtained, whose spectra can be used as the standard spectra of these compounds to analyze the Mössbauer spectra of Al alloys.  相似文献   

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为了分析Mo元素含量对液相烧结W—Ni—Fe重合金显微组织的影响和探讨Mo元素含量与基地相、析出相等各相组成的关系,以及了解合金于炉冷后在固相与基地相接口析出的金属间化合物相之形成机制,本研究使用具有相同基地相组成但不同Mo元素含量(Mo的原子数分数为15%~59%)的试片,以SEM、EMPA观察显微组织的变化,并使用XRD对金属间化合物析出相进行结构分析与鉴定,最后再以DTA热分析仪器量测合金的相变化温度,以厘清金属间化合物相的析出机制。试验结果显示,当合金中含有高比例的Mo元素时,烧结后在基地相中固溶的Mo元素与W Mo元素总和将随之升高,除了造成基地相的凝固温度下降以外,也形成大量的(W,Mo)0.5-(Ni,Fe)0.5 x(z=0~0.04)金属间化合物析出相,而此金属间化合物相中,Mo元素所占的比例会随着添加的Mo元素比例增加而呈线性上升。热分析结果显示,金属间化合物相的析出温度大约是在1349~1355℃之间,而基地相的凝固温度则从1415℃降低到1336℃。根据这些现象可以了解,金属间化合物相的形成机制与合金成分中的MMo/(Mw MMo)比值有关,当比值高于0.66时,金属间化合物相的析出机制为偏晶反应(monotectic reaction);当比值在0.5~0.66之间时,析出机制是属于共晶反应(eutectic reaction);当比值在0.34~0.5之间时,析出机制可能是共析反应(eutectoid reaction)或者是包析反应(peritectoid reaction);比值低于0.2时,则不会析出金属间化合物相。  相似文献   

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If the thermodynamic activity of the components in a binary metallic system A-B, which contains intermetallic compounds (A m B or AB l , where m, l = 1, 2, 3, …), is calculated on the basis of ideal associated solutions, reasonable accuracy may be obtained by means of the assumption that the chemical composition and thermodynamic properties of the associates are the same as for the intermetallic compounds.  相似文献   

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From thermodynamic data on seven CsCl-type intermetallic nonstoichiometric compounds, the nature of the defects present has been deduced and the defect concentrations, and free energies, enthalpies, and entropies of defect formation have been calculated. The compounds discussed include AuCd, AgMg, AuZn, FeAl, NiAl, CoAl, and PdAl. It is shown that the thermodynamic activities across the entire homogeneity range of a compound may be computed from a knowledge of the defect structure and free energies of defect formation and interaction.  相似文献   

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