Correlation of the physicomechanical properties and electronic structure of diffusion coatings

The high microhardness of iron borides FeB, formed in the boriding process, is due to the covalent bond of stable sp³-electron configurations. Some decrease in the microhardness of Fe₂B iron borides is due to the decrease in the statistical weight of stable sp³-configurations.The microhardness of silicide and aluminide phases is much lower than that of boride phases, because of the decrease in the probability of formation of stable sp³-configurations.Experimental investigation of the properties of chemical compounds in diffusion coatings confirm the correlation of the properties of these coatings with their structure.Presented at the Fifth All-Union Inter-Institute Seminar of the Physical Properties and Electron Structure of the Transition Metals and Their High-Melting Compounds and Alloys, Kiev, April 5–9, 1966.Translated from Poroshkovaya Metallurgiya, No. 12, pp. 92–94, December, 1966.     

Structural and phase characteristics and physicomechanical properties of detonation coatings in the system aluminum oxide-titanium oxide

Conclusions Powdered A1₂O₃—TiO₂ of the highest quality, characterized by a high degree of purity and homogeneity, are obtained by the method of crystallizing melts in a cold crucible. Detonation coatings from such powders have a uniform structure, uniform phase composition, and they have a complex of good physicomechanical properties: density, great separating strength of the substrate, mechanical strength. An addition of TiO₂ to powdered aluminum oxide stabilizes the crystal lattice of the phase -Al₂O₃ which is decisive for the heat and wear resistance of coatings. Moreover, an addition of TiO₂ increases the interparticular bond in the coating and its adhesive strength with the substrate. It is indispensable to point out the selectivity of the properties of detonation coatings type AT-40 in regard to the surfaces of the protected metals. The greatest strength of adheion with the coatings is found in chromium and titanium substrates; in steel, brass, and aluminum ones the strength is somewhat lower. The high selectivity of the properties is most probably due to the difference in sublimation energy and melting points of the materials of the substrate, their hardness and brittleness. It was noted that the adhesive bond between aluminum titanate coatings and the substrates is anomalously strong; this is due to the uniqueness of its properties. Coatings and substrates have a mutual effect on the strength and plastic properties. As a rule, coatings lower the bending strength of the substrate. An exception are chromium alloys which only become embrittled without loss of strength, and substrates of ductile low alloy steels which are somewhat strengthened by coatings.Translated from Poroshkovaya Metallurgiya, No. 5(281), pp. 59–64, May, 1986.     

Insight into physicomechanical and tribological properties of copper galvanic coatings formed with the addition of electroerosion copper nanopowder

The results of studying the properties of copper galvanic coatings fabricated using an L1-210 v2 galvanic installation (Italy) using the bright copper plating electrolyte produced by 24 Karata (Moscow) and the addition of electroerosion copper nanopowder fabricated by the electroerosion dispersion (EED) method using copper wire scrap in distilled water are given. An original setup developed by the authors (RF Patent 2449859) was used for the EED of conductors. The friction coefficient and wear factor found when testing coatings using a Tribometer automated friction machine (CSM Instruments, Switzerland) indicate the absence of substantial distinctions in the wear resistance of the samples. Surface hardness tests of the sample were performed using a DM-8 automated microhardness tester according to the micro-Vickers method with an indenter load of 25 g by ten imprints with a free selection of the indentation point according to GOST (State Standard) 9450–76. The indenter loading time was 15 s. It is established that the microhardness of a copper coating with the addition of copper nanoparticles is 15% higher than that of steel substrate and the sample with a standard copper coating.     

Mechanical properties of eutectic alloys β-NiAl + γ-Re and spray coatings

We have studied the structure and mechanical properties of eutectic alloys β-NiAl + γ-Re of the ternary system Ni-Al-Re. We have established that the best combination of mechanical characteristics, determined by local loading with a rigid indentor, is exhibited by the alloy containing 2.5 at.% Re, the structure of which consists of the eutectic β-NiAl + γ-Re. Rhenium inclusions can inhibit movement of cracks in the material, and also can play the role of traps for cracks. Brittle intercrystallite fracture is characteristic of the alloy consisting of one-phase intermetallic NiAl. Mixed fracture is typical of the eutectic alloy β-NiAl + γ-Re, with transcrystallite cleavage predominating. We have shown that plastic interlayers of a rhenium phase within the microstructure increase the crack resistance of a detonation coating made from eutectic alloys β-NiAl + γ-Re. __________ Translated from Poroshkovaya Metallurgiya, Nos. 3–4(448), pp. 78–87, March–April, 2006.     

Structure and physicomechanical properties of melt-spun TiNi-based alloys

The structure and physicomechanical properties (strength, plasticity, electrical resistivity, and shape memory effect) of TiNi-based binary (stoichiometric and nonstoichiometric compositions) and ternary (alloyed with copper, iron, and cobalt) alloys are studied in the initial (after melt quenching (MQ)) and annealed states. It is shown that the structural states formed upon MQ in all alloys are dependent on the cooling rate; subsequent heat treatment; and the contents of titanium, nickel, and alloying elements. Depending on the chemical compositions, MQ alloys undergo thermoelastic martensitic transformations with the formation of the R, B19′, or B19 martensite.     

喷射沉积AlFeVSi合金模压致密化工艺与模锻制品组织性能研究

采用喷射沉积工艺制备了快速凝固AlFeVSi合金圆锭坯.从锭坯上截取试样,采用模压工艺进行了高温(450和500℃)致密化.通过金相显微组织观察、透射电镜分析、扫描电镜分析、力学性能检测等手段,研究了在高温模压过程中的应力应变状态和金属流变规律对喷射沉积AlFeVSi合金坯的致密化过程与组织性能的影响,并采用铝包套高温(450℃)模锻工艺经将喷射沉积Al-9.20Fe-1.37V-2.30Si合金压实坯加工成完全致密化的模锻件.结果表明,高温模压可以明显提高沉积坯的致密度,但在有限的高向加载应力条件下难以使沉积坯达到理想的结合状态,与喷射沉积坯相比,虽然模压制品强度和塑性有明显提高,但仍处于低水平.喷射沉积坯经热压后,采用铝包套模锻成形,可以实现锻坯有效致密化和改善粉末间结合状态,明显提高材料屈服强度、抗拉强度和延伸率.喷射沉积Al-9.20Fe-1.37V-2.30Si合金直径=200 mm铝包套模锻件拉伸力学性能(σ0.2、σb和δ)可达如下指标:室温(25℃),411MPa、463MPa、9.7%,高温(350℃),180MPa、190MPa、8.9%.     

Some physicomechanical properties of ZrC-NbC-MoC1−x alloys

Conclusions Standard programs have been developed for the processing and geometric representation of data for systems consisting of more than two components. Composition—property surfaces have been constructed for the modulus of normal elasticity, microhardness, melting point, and lattice constant over the whole field of compositions of MoC_1–x-NbC-ZrC solid solutions. It is shown that the calculated polynomials match closely the actual response surfaces. The error involved in the prediction of values of properties has been calculated.Deceased.Translated from Poroshkovaya Metallurgiya, No. 12(180), pp. 76–82, December, 1977.     

添加元素Cu、Mo对镍基合金喷焊层组织和性能的影响

选择两种(Ni-A、Ni-B)成分不同的Ni基合金粉末,在STB A22钢基体上用火焰喷焊技术制备两种喷焊层.XRD和SEM背散射电子实验结果表明,喷焊层内的基体都是Ni和Ni₃Fe相,其中Ni-A的基体中含有少量Cu.在Ni-A、Ni-B的喷焊层内分布有大量富Cr硬质第二相,在Ni-A的喷焊层中,该相有两种形态,且含有较多Mo元素.在Ni-B的喷焊层中,第二相分布均匀,且无Mo元素.高温硬度实验表明,由于喷焊层中形成了富Cr硬质第二相,Ni-A、Ni-B喷焊层的硬度较高,而由于Ni-A第二相中含有较多Mo元素,Ni-A的高温硬度比Ni-B高,两种喷焊层的高温硬度均比基材常温时高70%以上.     

Formation of the physicomechanical properties in high-strength invar alloys

New technology for the production of high-strength Invar alloys containing carbon, cobalt, and vanadium is considered. The formation of the alloys’ mechanical properties is discussed. A basic system for the production of Invar blanks at metallurgical plants is described.     

Feasibility of manufacture of hard-alloy parts with variable physicomechanical properties

Summary The results are presented of an investigation into the conditions of preparation of hard-alloy parts whose physicomechanical properties vary along their height. The experimental procedure is described in detail, and full results are given.Translated from Poroshkovaya Metallurgiya, No. 9(45), pp. 37–42, September, 1966.     

Synthesis and physicomechanical properties of B4C-VB2 composites

We have studied the properties of composites in the B₄C-VB₂-C system, obtained by reaction synthesis with hot pressing. We have established that the presence of free carbon and vanadium boride in the ceramic makes it possible to activate the sintering process and to obtain a dense, highly dispersed ceramic with good structural homogeneity parameters for lower isothermal holding temperatures. The composite ceramic has higher hardness and bending strength over a broad range of vanadium boride content than the monophase ceramic based on boron carbide. The strength properties of the composite ceramic containing up to 8 vol.% vanadium boride are improved by means of a mechanism involving propagating cracks bending around obstacles. When the VB₂ concentration increases further, the properties of the composite are determined by a microcracking mechanism. In this case, we observe relatively small changes in the elastic characteristics, which depend linearly on the composition of the ceramic. Introducing vanadium boride into the material is also accompanied by an increase in the contact and microstructural strengths. The results obtained indicate that the new composite material is promising for fabricating wear-resistant and shock-resistant components of various structures and machines. __________ Translated from Poroshkovaya Metallurgiya, Nos. 1–2(447), pp. 59–72, January–February, 2006.     

Current-conducting coatings based on heat-resistant titanium compounds obtained by self-propagating high-temperature synthesis

Titanium carbide, silicide, and carbosilicide are obtained by self-propagating high-temperature synthesis. The microstructure, phase composition, and properties of these compounds are given. Materials in the form of powders were used to form current-conducting polymer doughs. The influence of the type and content of the filling agent, the temperature of the thermal treatment, and the composition of the polymer binder on the electric resistance of polymer coatings is investigated. It is established that the binders that provide the lowest resistance of doughs are PMPP and PPG polymers, and the corresponding filling agent is titanium carbosilicide. The working temperature of doughs containing PMFP and PFG should not exceed 250°C, that of SKTN should not exceed 150°C, and the mixture of epoxy resin and PMFP and PFG should not exceed 300°C.