Properties of the surface layer on copper formed after deposition and thermal treatment of aluminum gas-thermal coating

The fabrication and properties of the surface layer on copper are investigated after deposition and thermal treatment of the aluminum gas-thermal coating. This process leads to the formation of a protective diffusion layer having high physical, mechanical, and performance characteristics.     

Effect of coating porosity on the process of heat transfer with gas-thermal deposition

Features are considered for the thermal state of layered-inhomogeneous systems of a multilayer coating—underlayer—base with plasma deposition of cladding composite powders. Typical results are presented for mathematical modeling of the quasistationary process of heat transfer for the system in question. Regularities of the effect of coating porosity on the temperature schedule for the system and the effect of coating thickness on porosity are studied.Polytechnic Institute, Kiev. Institute of Thermophysical Technology, Ukrainian Academy of Sciences, Kiev. Institute of Electric Welding, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, No. 2(362), pp. 22–26, February, 1993.     

The influence of aluminum on the nickel and chromium diffusion into copper during the deposition and thermal treatment of gas-thermal coatings

The method of electron probe microanalysis is applied to analyze the distribution of elements over the diffusion layer obtained by the deposition on copper of gas-thermal coatings involving Al, Ni, Cr, Fe and subsequent thermal treatment. It is established that the penetration depth and concentration of the coating elements reach their maximal values in the case of the presence of an aluminum sublayer.     

Effect of heat treatment and diffusion welding conditions on the structure and properties of porous material workpieces made of titanium fibers

The effect of the diffusion welding conditions on the structure and properties of a porous material (PM) made of titanium fibers is studied. It is shown that the use of fibers produced by melt quenching and then joined to form workpieces or articles by diffusion welding can be a promising trend in the production of PMs for medicine applications. A change in the solidification rate of fibers and their contact substantially affects the mechanical properties of PM workpieces. As the diffusion welding temperature of both sheet and cylindrical workpieces increases, the strength of PM increases and the plasticity of PM decreases.     

TiB whisker coating on titanium surfaces by solid-state diffusion: Synthesis,microstructure, and mechanical properties

The study demonstrates the feasibility of synthesizing TiB whiskers on titanium (Ti) surfaces by solid-state diffusion to form a hard and wear-resistant coating. The microstructural and mechanical properties of the TiB coating layer have also been investigated. The TiB coating was formed by the solid-state diffusion of boron (B) from a powder mixture containing amorphous boron, Na₂CO₃ powder, and charcoal (activated) powder. The diffusion process was carried out at various temperatures ranging from 800 °C to 1000 °C for various periods of time ranging from 1 to 24 hours. The amount of Na₂CO₃ in the mixture was also varied. It has been found that pristine and extremely fine TiB whiskers form on the surfaces of titanium, with the whiskers growing more or less normal to the surface. A maximum coating thickness of about 218 μm was observed for the pack diffusion conditions at 850 °C for 24 hours with 15 pct Na₂CO₃. The kinetics of TiB formation was found to follow the growth rates in bulk composites. The X-ray diffraction (XRD) patterns of the coatings revealed the dominant TiB peaks with a very few TiB₂ peaks, with small intensity at higher temperature and time. The surface hardness of the coated layer increased to a Vickers hardness of about 550 kgf/mm² due to the presence of TiB whiskers in the coating. It is shown that pack diffusion of boron in the solid state is a simple and very effective means of generating hard and wear-resistant coatings on titanium.     

热处理制度对汽车用TC6钛合金组织及性能的影响

采用四种不同热处理制度对汽车用TC6钛合金棒材进行了等温退火试验,并进行了试样显微组织、耐磨损性能和耐腐蚀性能测试与分析.结果 表明,采用"870℃保温1.5 h,炉冷至600℃保温2h,空冷"热处理制度(1#试样)时,合金的耐磨损和耐腐蚀性能最差;采用"900℃保温1.5h,炉冷至600℃保温2h,空冷"热处理制度(...     

Influence of nonequilibrium second-phase particles formed during solidification upon the mechanical behavior of an aluminum alloy

The mechanical behavior of a wrought high strength aluminum alloy is examined as a function of the concentration of second-phase microconstituents. These second-phase particles are located in grain boundaries and interdendritic sites. Their concentration was varied by thermal-mechanical processing. In the areas of strengths, ductility, crack toughness, fatigue, and stress corrosion cracking, empirical results are presented and discussed. Observations are made on changes in the anisotropic character of this category of material with lower concentrations of second phases. Formerly Research Advisor, Frankford Arsenal. This paper is based on an invited talk presented at a symposium on Homogenization of Alloys, sponsored by the IMD Heat Treatment Committee, and held on May 11,1970, at the spring meeting of The Metallurgical Society of AIME, in Las Vegas, Nev.     

Effect of the coating procedure on the properties of easily worn gas-thermal sealing coatings involving the use of solid lubricant

Translated from Poroshkovaya Metallurgiya, No. 12 (348), pp. 46–51, December, 1991.     

液相沉积制备TiO_2/Al颜料及其在自清洁涂料中的应用

以硫酸氧钛和氢氧化钠为主要原料,采用液相沉积法在片状Al粉表面包覆TiO2,制备TiO2/Al颜料,并进一步制得含有该颜料的自清洁涂料。以油酸为污染模拟物,用油酸的分解率作为评价手段,考察反应pH、煅烧温度、涂膜厚度对该涂料自清洁性能的影响。通过XRD仪对颜料结构进行表征,并对颜料的分散性和耐腐蚀性能进行研究。结果表明:在pH为4.5、煅烧温度为600℃条件下TiO2/Al表面的TiO2晶型为锐钛矿型,因而具有最强的自清洁能力。当颜料涂膜厚75μm时,经紫外灯光照3 h后油酸的分解率达到91%。用752S型可见分光光度计于λ=420 nm处分别测得Al粉和TiO2/Al颜料的透光率,来表征其分散性,结果证明Al粉的透光率比TiO2/Al高30%;用浓度0.1 mol/L的HCl溶液进行腐蚀实验,TiO2/Al颜料的耐腐蚀性能显著提高。     

Effects of oxygen and heat treatment on the mechanical properties of alpha and beta titanium alloys

Two alloys, Ti-6Al-2V and Ti-2Al-16V, simulating the alpha and beta phases of Ti-6A1-4V, respectively, were prepared with oxygen concentrations from 0.07 to 0.65 wt pct (0.20 to 1.83 at. pct). Their microstructure, deformation behavior, and strength were investigated with X-ray diffraction, microscopy, and mechanical tests to determine the effects of oxygen concentration and heat treatment. In both alloys the hardness increases in identical fashion with the square root of oxygen concentration. The alloys' strengths also depend on heat treatment, but in different ways. Whereas the alpha alloy is non-age-hardenable, the beta alloy's strength can be doubled by aging. The hardening effect of oxygen is generally unaffected by heat treatment, except for the alloys with the highest oxygen concentrations. During aging of the alpha a small amount of Ti₃Al can form, and slight age-hardening occurs. The ductility of the alpha alloy is little affected by aging. On the other hand, oxygen causes a change from good ductility at low oxygen concentration (0.07 wt pct) to total brittleness at 0.65 wt pct oxygen, independent of heat treatment. In the beta alloy there are complex phase transformations depending on heat treatment. Its deformation behavior varies from very ductile in solutiontreated and quenched (STQ) condition to totally brittle in aged conditions. The aging embrittlement appears to be caused by alpha and some omega precipitation. Decoration of the beta grain boundaries with precipitates accounts for the intergranular brittle fracture. Oxygen, on the other hand, is not an embrittler, although it reduces the ductility of the beta alloy.     

热处理对超音速火焰喷涂 NiCoCrAlY 涂层组织性能的影响

采用超音速火焰喷涂制备了NiCoCrAlY合金涂层,采用真空热处理工艺对涂层进行了后处理,研究了热处理前后涂层的结构形貌、界面以及涂层结合强度的变化。研究结果表明:热处理后涂层的缺陷和孔隙由8.3%降低至1.4%;SEM和EDS分析表明,涂层与基材之间发生了元素互扩散,涂层与基体形成了约20μm的扩散层,涂层的结合强度由42.1MPa提高到55.6MPa。热处理后,涂层/基体界面形成的扩散层改善了界面结合状态,有助于消除界面处的残余应力,并形成冶金结合,从而提高涂层的结合强度。     

热处理工艺对ZTC4钛合金显微组织及性能的影响研究

采用金相显微镜(OM)研究了热处理制度对ZTC4钛合金显微组织的演变规律,以及显微组织对力学性能的影响关系.结果表明:ZTC4钛合金铸件由马氏体α'相组成,进行退火以及热等静压+退火热处理后,显微组织均为典型魏氏组织.ZTC4钛合金铸件退火后抗拉强度可达955 MPa,其延伸率和断面收缩率分别为8.8％和13.1％.采...     

热处理制度对7039铝合金冲击性能及组织的影响

将7039铝合金热轧板材在470℃/2 h条件下固溶后,分别进行T6处理、T73处理以及RRA处理.利用Hopkinson压杆技术对3种热处理态的7039铝合金进行冲击压缩实验,用光学显微镜和透射电镜对冲击后的试样进行组织观察,分析热处理制度对合金动态应力-应变行为和微观组织的影响.结果表明:经T6处理的7039铝合金在高速冲击加载时的绝热剪切敏感性明显低于T73和RRA处理的合金,经RRA处理的合金绝热剪切敏感性最大;不同热处珲状态的合金在应变率为3 000 s-1时,组织中均产生绝热剪切带以及变形带;合金在高速冲击加载过程中产生的绝热剪切带内部组织主要是一种强同复组织.     

The influence of heat treatment on the structure and properties of a near-α titanium alloy

The microstructure and tensile properties of a near-α titanium alloy, IMI-829 (Ti-6.1 wt pct Al-3.2 wt pct Zr-3.3 wt pct Sn-0.5 wt pct Mo-1 wt pct Nb-0.32 wt pct Si) have been studied after solutionizing (and no subsequent aging) at two different temperatures separately, one above the β transus (1050 °C) and another below the β transus (975 °C) followed by various cooling rates (furnace, air, oil, or water). While 1050 °C treatment resulted in coarse Widmanstätten structures on furnace or air cooling, fine Widmanstätten structure on oil quenching and martensitic structure on water quenching, 975 °C treatment produced duplex microstructures consisting of equiaxed alpha and partially transformed beta phases. Transmission electron microscopy studies revealed the morphology, size, and distribution of the α, β, and martensite phases and also the presence of small ellipsoidal suicide particles and an interface phase with fcc structure at almost all α-β interfaces. The oil quenched structure from 1050 °C has been found to be a mixture of fine Widmanstätten α coexisting with martensite laths and retained beta at the lath boundaries. Silicides with hcp structure of about 0.4 μm size were observed in specimens solution treated at 975 °C. The interface phase is seen in all slowly-cooled specimens. The YS and UTS are superior for 975 °C treatment compared to 1050 °C treatment after water quenching or oil quenching. The tensile ductility values are superior for any cooling rate after 975 °C solution treatment as compared to 1050 °C solution treatment. The specimens failed in tension diagonally by shear after 1050 °C treatment and by cup and cone fracture after 975 °C treatment. In all cases fracture has taken place by microvoid coalescence and in most cases, along the α-β boundaries.     

热处理工艺对近α钛合金组织与性能的影响

研究了固溶和时效工艺参数对一种近α钛合金Ti-5Al-2Nb-2Zr-1.5Mo显微组织与力学性能的影响.结果表明:在α+β两相区,随着固溶温度的升高,初生α相含量(体积分数,下同)减少,亚稳相含量增加,冷却过程中分解的针状马氏体α'相使合金的硬度升高;时效温度的变化通过影响α'相分解析出次生α相的尺寸、数量及分布方式...     

Kinetics of layer growth and multiphase diffusion in ion- nitrided titanium

Pure titanium specimens were ion nitrided in a nitrogen plasma in the temperature range of 800 ‡C to 1080 ‡C at various nitrogen partial pressures. During ion nitriding, titanium nitrides TiN and Tiin2N and nitrogen solid solution layers (α and Β) were formed consistent with the equilibrium phase diagram. The kinetics of growth of these layers were studied as a function temperature and ion-nitriding parameters. An analytical diffusion model for multiphase diffusion was used to calculate the diffusion coefficients of nitrogen in the phases of the Ti-TiN system from layer growth experiments. Using the layer growth data, the temperature dependence of nitrogen diffusion in TiN (δ), Ti₂N (ε), and α titanium was found to obey the following relations: Dinδ=4.4±1.62 × 10su-5 exp-36,500±1400/RT Dinε=2.7±1.05 ×10su-3 exp-35,760±2500/RT Dinα=0.96±0.08 × exp-51,280-505/RT Concentration profiles of nitrogen were measured in specimens ion nitrided at 900 ‡C. The profiles were in good agreement with the predicted ones at high nitrogen concentrations. How-ever, at low nitrogen concentrations, a deviation was observed, assumed to be due to a con-centration dependence of nitrogen diffusion in a titanium. Formerly Graduate Student, New Mexico Institute of Mining and Technology     

Effect of heat treatment conditions on the structure and mechanical properties of a cast Al-Li-Cu aluminum alloy

Quenching and one- and two-stage aging conditions are found for a high-strength Al-Li-Cu cast alloy with a low density from the results of studying its structure, mechanical properties, and aging kinetics.     

喷射成形6061铝合金的显微组织与力学性能研究

研究了喷射成形6061铝合金的显微组织和力学性能,并与熔铸成形6061铝合金进行对比。结果表明,喷射成形6061铝合金显微组织较好,但由于其还未进行致密化处理,组织内存在一定的孔隙,各项拉伸性能低于熔铸成形6061铝合金。