Structural modification of TiAlN coatings by preliminary Ti Ion bombardment of a steel substrate

The TiAlN coatings deposited onto steel 12Cr18Ni9Ti substrates before and after preliminary treatment by Ti ion beams are studied by X-ray diffraction, transmission electron microscopy, atomic force microscopy, and nanoindentation. The modification of the surface layer of a substrate is shown to change the structure and the preferred orientation of the coatings. The mechanical properties of the TiAlN coatings are found to depend substantially on the ion bombardment time.     

脉冲高能量密度等离子体沉积(Ti,Al)N薄膜组织及其性能研究

利用脉冲高能量密度等离子体技术在室温条件下在45＃钢基材表面沉积了高硬度耐腐蚀(Ti, Al)N薄膜. 利用扫描电子显微镜、X射线衍射、X射线光电子能谱、俄歇电子能谱分析了薄膜的显微组织.利用纳米压痕仪测试了薄膜的纳米硬度.测试了薄膜在05mol/L H2SO4水溶液中的耐蚀性. 测试结果表明：薄膜主要组成相为(Ti, Al)N，同时含有少量的AlN,薄膜的纳米硬度高达26 GPa,薄膜具有良好的耐蚀性，与1Cr18Ni9Ti奥氏体不锈钢相比，耐蚀性提高了一个数量级. 关键词： 脉冲高能量密度等离子体 薄膜 纳米硬度 耐蚀性     

Nitriding of Stainless Steel in Electron-Beam Plasma in the Pulsed and DC Generation Modes

The influence of electron-beam parameters on the thickness and phase composition of a hardened layer formed upon the nitriding of austenitic stainless steel 12Cr18Ni10Ti in plasma produced by a beam in a low-pressure (3 Pa) nitrogen-argon mixture is studied. The results obtained in the DC and pulse-periodic modes of beam generation with the same mean current and electron energy are compared. In this case the negative bias voltage applied to the samples is 100 V. The nitriding temperature of 400°C is maintained at a mean beam current of 2.6 A and various combinations of frequency (100–500 Hz) and current pulse durations (0.1–0.3 ms) with an amplitude of 80 A. The mean ion-plasma current densities in the DC and pulsed modes are close in magnitude (2–3 mA/cm² at 400°C). The high pulsed ion-current density (35–70 mA/cm²) creates conditions under which the surface sputtering rate during the pulse exceeds the growth rate of the nitrided layer. The nitriding of steel in the pulsed and DC modes over four hours gives the same result. Hardened layers with a thickness of 7–8 μm and a microhardness of the surface component of 15 ± 1 GPa in which the main phase is a supersaturated nitrogen solid solution (expanded austenite) are formed. A possible explanation is that nitriding in an electron-beam plasma proceeds mainly under the action of long-lived active neutral nitrogen particles rather than as a result of ion bombardment.     

One-dimensional migration of interstitial clusters in SUS316L and its model alloys under electron irradiation

The one-dimensional (1D) migration of interstitial clusters in austenitic stainless steel SUS316L and its model alloys, namely, Fe–18Cr–13Ni, Fe–18Cr–13Ni–0.012C, and Fe–18Cr–13Ni–1.7Mn (mass %), was examined using in situ observation by high-voltage electron microscopy. Such 1D migration was confirmed to occur along the ?110? direction at irregular intervals in all these alloys under 1250-kV electron irradiation at room temperature. The frequency of 1D migration was found proportional to electron beam intensity, and was about 1/10 that in high-purity iron under the same irradiation intensity. The distance of 1D migration in the four alloys was less than 10?nm, which was much shorter than that in high-purity iron. No clear difference in the frequency or distance of 1D migration was observed among the four alloys, suggesting that minor solute/impurity elements have no apparent effect on 1D migration in SUS316L.     

Formation of surface gradient structural-phase states under electron-beam treatment of stainless steel

The structural-phase states of steel 08X18H10T (0.08% C, 18% Cr, 10% Ni, 1% Ti) subjected to pulse electron beam treatment in the regime of surface layer melting is investigated using the methods of optical and electron microscopy. The regularities of variations in the phase composition and the state of the defect substructure moving away from the irradiation surface up to a 200-μm depth are revealed.     

Effect of high-temperature thermomechanical treatment in the austenite region on microstructure and mechanical properties of low-activated 12% chromium ferritic-martensitic steel EK-181

The effect of high-temperature thermomechanical treatment with deformation in the austenite region on the microstructure and mechanical properties in low-activated 12% chromium ferritic-martensitic steel EK-181 (Fe–12Cr–2W–V–Ta–B) has been investigated. This treatment leads to a significant increase (compared to traditional regime of treatment) in the density of dislocations, dispersity, and volume fraction of nanosized particles V(C,N) and, as a consequence, to an increase in the yield strength while maintaining a sufficient reserve of ductility.     

Nuclear Physical Properties of Austenitic Nickel and Manganese Steels under Neutron Irradiation in Nuclear Fission (Fast) and Fusion Reactors

Physics of Atomic Nuclei - The nuclear physical properties of austenitic chromium-nickel steel EK-164 (Fe–16Cr–19Ni–2Mo–2Mn–Nb–Ti–B) and its...     

ICP法测定超临界水氧化设备腐蚀液中铜、铬、铝、镍、钛

采用光谱法研究了超临界水氧化设备腐蚀液中Cu,Cr,Al,Ni和Ti元素的含量,分析判断不锈钢设备腐蚀状况及其因素。结果表明,超临界设备不锈钢材料主要成分元素Cr在超临界水中有不同程度的溶解,并且溶解程度随温度和压力升高而增大。     

Microstructure and mechanical properties of nano-Y2O3 dispersed ferritic steel synthesized by mechanical alloying and consolidated by pulse plasma sintering

Ferritic steel with compositions 83.0Fe–13.5Cr–2.0Al–0.5Ti (alloy A), 79.0Fe–17.5Cr–2.0Al–0.5Ti (alloy B), 75.0Fe–21.5Cr–2.0Al–0.5Ti (alloy C) and 71.0Fe–25.5Cr–2.0Al–0.5Ti (alloy D) (all in wt%) each with a 1.0?wt% nano-Y₂O₃ dispersion were synthesized by mechanical alloying and consolidated by pulse plasma sintering at 600, 800 and 1000°C using a 75-MPa uniaxial pressure applied for 5?min and a 70-kA pulse current at 3?Hz pulse frequency. X-ray diffraction, scanning and transmission electron microscopy and energy disperse spectroscopy techniques have been used to characterize the microstructural and phase evolution of all the alloys at different stages of mechano-chemical synthesis and consolidation. Mechanical properties in terms of hardness, compressive strength, yield strength and Young's modulus were determined using a micro/nano-indenter and universal testing machine. All ferritic alloys recorded very high levels of compressive strength (850–2850?MPa), yield strength (500–1556?MPa), Young's modulus (175–250?GPa) and nanoindentation hardness (9.5–15.5?GPa), with up to 1–1.5 times greater strength than other oxide dispersion-strengthened ferritic steels (<1200?MPa). These extraordinary levels of mechanical properties can be attributed to the typical microstructure of uniform dispersion of 10–20-nm Y₂Ti₂O₇ or Y₂O₃ particles in a high-alloy ferritic matrix.     

Change of mechanical properties of Fe-Cr-Ni steel after corrosion of steel in chlorine medium without and with magnetic field

The influence of weak magnetic field (B = 0.05 T) on mechanical properties, i.e. the torsional and twisting strength, of Fe-Cr-Ni steel (18.2% Cr, 9.4% Ni, 0.08% Mn, 0.6% Ti, 0.04% Co) has been investigated. When a permanent magnetic field is used, the steel wire, treated in acidic chloride solutions (11% FeCl₃·6H₂O or 11% FeCl₃·6H₂O + 3% NaCl), loses its mechanical properties more rapidly than if the magnetic field is not used. It suggests that the loss of mechanical properties of the wire is connected with peculiarities of formation of pitting. When pitting is formed without magnetic field, it penetrates preferably in depth of steel, meanwhile in the magnetic field pitting is formed preferably on the surface area.     

Forward and backward electron emission cross-sections for 23 MeVu<Superscript>-1</Superscript> C,Ni and Au projectiles traversing C,Al , Ni,Ag , Au and Bi foils

A rather complete experimental study of forward and backward electron velocity spectra from thin foils bombarded with ions at constant velocity of 30 atomic units (23MeV u^-1) was performed. Three different beams ( ¹²C³⁺ , ⁵⁸Ni¹⁴⁺ and ¹⁹⁷Au³⁶⁺ and six different targets ( ¹²C , ²⁷Al , ^natNi , ^natAg , ¹⁹⁷Au and ²⁰⁹Bi of approximately 90μg cm^-2 thickness were used. This procedure allowed to study the evolution of electron emission (velocity and angular distributions) for the [projectile; target] matrix [ C , Ni , Au ; C , Al , Ni , Ag , Au , Bi ] in a wide angular range. The projectile and target dependence of absolute cross-sections for binary encounter-, Auger- and backward-emitted electrons are analyzed.     

An AES and ESCA study of GCr15 steel coated with Ti,Cr and bombarded by N+ and Ar+

GCr15 steel specimens coated with Ti, Cr and bombarded with N⁺, Ar⁺ were analyzed by AES and ESCA (PHI-550). The results show that (1) the specimens bombarded with N⁺ have improved surface mechanical properties compared to those bombarded with Ar⁺; (2) the changes in the surface properties are related to the composition of the surface layer, mainly to TiO₂, TiN, Cr₂O₃, and other compounds. Also, the presence of carbon is found to be advantageous in modifying GCr15 bearing steel.     

Accuracy Studies in Inductively Coupled Plasma Atomic Emission Spectrometry Determination of Eight Elements in Standard Steel and Nickel Alloy High Solid Solutions

Abstract

The determination of Al, Cr, Cu, Fe, Mn, Mo, Ni, and Ti in digested stainless steel and nickel alloys using inductively coupled plasma atomic emission spectrometry with dual analytical lines was performed. Accuracy of the high solid solutions was assessed by comparison to standard values and found to be excellent.     

Surface energy of M2AC(0 0 0 1) determined by density functional theory (M = Ti, V, Cr; A = Al, Ga, Ge)

We have studied the correlation between the valence electron configuration and the electronic structure of M₂AC(0 0 0 1) surfaces (M = Ti, V, Cr; A = Al, Ga, Ge) by density functional theory. The A surface termination is the most stable configuration for all systems studied according to our surface energy data. As the M valence electron population is increased, the surface energy increases by 22% and 12% for A = Al and Ga, respectively, while it decreases by 29% for A = Ge. This can be understood by evaluating the valence electron concentration induced changes in the surface density of states. Antibonding surface Md-Ap states are present as Ti is substituted by Cr in M₂AC(0 0 0 1) for A = Al and Ga, while antibonding surface Md-Ap states are not present as Ti is substituted by Cr in M₂GeC(0 0 0 1).     

Phase transformation in Ni–Mn–Sn ferromagnetic shape memory alloy thin films induced by dense ionization

The effects of 200 MeV Au ions irradiation on the structural and magnetic properties of Ni–Mn–Sn ferromagnetic shape memory alloy (FSMA) thin films have been systematically investigated. In order to understand the role of initial microstructure and phase of the film with respect to high energy irradiation, the two types of Ni–Mn–Sn FSMA films having different phases at room temperature were irradiated, one in martensite phase (Ni_58.9Mn_28.0Sn_13.1) and other in austenite phase (Ni₅₀Mn_35.6Sn_14.4). Transmission electron microscope (TEM) and scanning electron microscope (SEM) images along with the diffraction patterns of X-rays and electrons confirm that martensite phase transforms to austenite phase at a fluence of 6×10¹² ions/cm² and a complete amorphization occurs at a fluence of 3×10¹³ ions/cm², whereas ion irradiation has a minimal effect on the austenitic structure (Ni₅₀Mn_35.6Sn_14.4). Thermo-magnetic measurements also support the above mentioned behaviour of Ni–Mn–Sn FSMA films with increasing fluence of 200 MeV Au ions. The results are explained on the basis of thermal spike model considering the core and halo regions of ion tracks in FSMA materials.     

Improved device performance in nonpolar a ‐plane GaN LEDs using a Ni/Al/Ni/Au n‐type ohmic contact

The authors report upon the increased light‐output power (P_out) via a reduction in the forward voltage (V_f) for nonpolar a ‐plane GaN LEDs using Ni/Al/Ni/Au n‐type ohmic contacts. The specific contact resistivity of the Ni/Al/Ni/Au contact is found to be as low as 5.6 × 10^–5 whereas that of a typical Ti/Al/Ni/Au contact is 6.8 × 10^–4 Ω cm², after annealing at 700 °C. The X‐ray photoelectron spectroscopy results show that the upward surface band bending is less pronounced for the Ni/Al contact compared to the Ti/Al contact, leading to a decrease in the effective Schottky barrier height (SBH). The V_f of the nonpolar LEDs decreases by 10% and P_out increases by 15% when the Ni/Al/Ni/Au scheme is used instead of the typical Ti/Al/Ni/Au metal scheme. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Influence of laser treatment on the wear of friction surfaces of 40Cr steel

The friction wear of surfaces of 40Cr (40Khr) structural steel and 12Cr18Ni10Ti (12Kh18N10T) stainless steel is investigated. It is established, by comparison of the wear of initially annealed 40Cr steel after hardening by radiation from a CO₂ laser to various degrees of surface microhardness and separately after volume heat treatment, that the wear is due to fatigue in the entire range of microhardness, regardless of the dispersive properties of the structures. It is shown that the resistance to wear tends to increase with increase of the microhardness of the bearing surfaces. The dependence of the rate of wear on the surface microhardness is obtained. It is found that the wear process is accompanied by formation of a special structurally stressed state in the Saint-Venant region; this state is characterized by a constant hardness level independently of the preceding state of the material.Translation of Preprint No. 196, Lebedev Institute of Physics, Academy of Sciences, USSR, Moscow (1990).     

Study of Ti/Au,Ti/Al/Au,and Ti/Al/Ni/Au ohmic contacts to <Emphasis Type="Italic">n</Emphasis>-GaN

The contacts of Ti/Au, Ti/Al/Au, and Ti/Al/Ni/Au films deposited on n-GaN were studied by current–voltage (I–V) and transmission-line-method measurements. The effect of annealing temperature on specific contact resistivity has been investigated by changing the annealing temperature from 400 to 900 °C. Ti/Al/Au and Ti/Al/Ni/Au films were superior to the bilayer (Ti/Au) in ohmic contact characteristics and thermal stability. The Ti/Al/Ni/Au composite showed the best thermal stability due to the fact that Ni plays a more important role than the alloy of Ti/Al in preventing the interdiffusion of Ti, Al, and Au. The lowest contact resistivity (10^-7cm²) to n-GaN was obtained for the Ti/Al/Ni/Au sample by short-time/high-temperature annealing. The formation mechanism of ohmic contacts to n-GaN is also discussed. PACS 73.40.Cg; 73.61.Ey     

Microstructure and mechanical properties of V–4Ti–4Cr alloy as a function of the chemical heat treatment regimes

The regularities of the formation of a heterophase structure and mechanical properties of V–4Ti–4Cr alloy as a function of thermomechanical and chemical heat treatments are studied. The regimes of thermomechanical treatment which provide the formation of a heterophase structure with a homogeneous volume distribution of oxycarbonitride nanoparticles with a size of about 10 nm and an increase in the volume content and thermal stability of this phase and which provide an increase in the temperature of alloy recrystallization are developed. The formation of the heterophase structure results in a substantial (up to 70%) increase in the short-term high-temperature strength of the alloy at T = 800°C. The increase in the strength is achieved while keeping a rather high level of plasticity.     

Co、Ni和Ga合金化对DO_(19)-Ti_3Al弹性性能影响的第一性原理研究

采用第一性原理的方法研究了Co、Ni和Ga元素对DO_(19)-Ti_3Al晶体的弹性性能的影响,结果表明:Co和Ni原子倾向于置换Ti原子而Ga原子则更倾向于置换Al原子;Co和Ni元素固溶可以减弱晶体内部电子杂化效应从而增大Ti_3Al晶体的本征塑性,其中Co元素的对晶体的本征塑性的增大效果显著;Ga元素固溶后Ti_3Al晶体的强度和硬度将得到提高.