Effect of Straining Conditions on Structural Characteristics of Pressed Shape Memory Alloy 45% Ti – 45% Ni – 10% Nb

Metal Science and Heat Treatment - The effect of the temperature-and-rate conditions of straining on the structural characteristics of pressed alloy 45% Ti – 45% Ni – 10% Nb is studied....     

训练对Fe14Mn6Si9Cr5Ni合金形状记忆效应的影响

研究了训练，预应变量和退火温度对Ｆｅ１４Ｍｎ６Ｓｉ９Ｃｒ５Ｎｉ合金的形状记忆效应，绝对形状回复率和超弹性的影响，测定了合金的蠕变和应力松驰特性，讨论了降温ε马氏体对形状记忆效应的间接贡献。研究结果表明，该合金特殊训练方法能够获得大于６％的形状记忆效应并具有较好的蠕变抗力。     

训练对Fe14Mn6Si9Cr5Ni合金形状记忆效应的影响

研究了训练、预应变量和退火温度对Ｆｅ１４Ｍｎ６Ｓｉ９Ｃｒ５Ｎｉ合金的形状记忆效应、绝对形状回复率和超弹性的影响，测定了合金的蠕变和应力松驰特性，讨论了降温ε马氏体对形状记忆效应的间接贡献。研究结果表明，该合金经特殊训练方法能够获得大于６％的形状记忆效应并具有较好的蠕变抗力。     

Effect of Compaction Pressure on Mechanical Properties of Powder Steel 0.06% C – 22% Cr – 13% Ni – 5% Mn – 2% Mo Obtained by Mechanical Alloying Followed by Annealing

Metal Science and Heat Treatment - The mechanical properties of a powder steel containing 0.06% C, 22% Cr, 13% Ni, 5% Mn and 2% Mo (UNS S20910) and manufactured by mechanical alloying with...     

Study of the Properties of a High-Temperature 50Ti–40Pd–10Ni Shape Memory Alloy

Combined studies of the properties of the 50Ti–40Pd–10Ni alloy with a high-temperature shape memory effect have been carried out. The elemental and phase compositions and its mechanical and thermomechanical characteristics have been determined. Samples cut from the strip with a thickness of 2.04 mm have been studied. The phase transformations are in the range of M_f = 371.3°С to A_f = 436.9°С. These are acceptable values. The maximum values of the shape memory effect ε_SME and of the degree of shape recovery η_SME are 3.9 and 49%, respectively. These values are insufficient to create workable safety devices. These characteristics can be improved via optimal changes in the elemental composition of the shape memory alloy and by an adequate choice of the regimes of heat treatment and of the regimes of providing strain in the investigated objects. The results of these studies are necessary in order to develop different devices used in nuclear power plants.     

Magnetic Properties of Hard Magnetic Powder Alloy Fe – 27% Cr – 10% Co (27Kh10KA)

Metal Science and Heat Treatment - Magnetic hysteresis properties (residual induction Br, coercivity Hc and maximum energy product (BH )max) of Fe – 27% Cr – 10% Co (27Kh10KA) hard...     

Corrosion Resistance of Materials Obtained By Electron-Beam Cladding of Fe – Cr – Ni – Ti Powder Mixtures

Metal Science and Heat Treatment - Corrosion resistance of surface layers of structural steel 12KhN3A modified with chromium, nickel and titanium using the process of non-vacuum electron beam...     

Influence of Alloying Element Addition on Cu–Al–Ni High-Temperature Shape Memory Alloy without Second Phase Formation

In this study,the effects of rare earth Gd and Fe elements on the microstructure,the mechanical properties and the shape memory effect of Cu–11.9Al–3.8Ni high-temperature shape memory alloy were investigated by optical microscopy,scanning electron microscopy,X-ray diffraction and compression test.The microstructure observation results showed that both Cu–11.9Al–3.8Ni–0.2Gd and Cu–11.9Al–3.8Ni–2.0Fe–0.2Gd alloys displayed the fine grain and singlephase b01martensite,and their grain size was about several hundred microns,one order of the magnitude smaller than that of Cu–11.9Al–3.8Ni alloy.The compression test results proved that the mechanical properties of Cu–11.9Al–3.8Ni alloy were dramatically improved by alloying element additions due to grain refinement and solid solution strengthening,and the compressive fracture strains of Cu–11.9Al–3.8Ni–0.2Gd and Cu–11.9Al–3.8Ni–2.0Fe–0.2Gd were 12.0%and 17.8%,respectively.When the pre-strain was 10%,the reversible strains of 5.4%and 5.9%were obtained for Cu–11.9Al–3.8Ni–0.2Gd and Cu–11.9Al–3.8Ni–2.0Fe–0.2Gd alloys after being heated to 500°C for 1 min,and the obvious two-way shape memory effect was also observed.     

热处理对Fe17Mn5Si8Cr5Ni形状记忆合金回复应力的影响

研究了热处理对Fe17Mn5Si8Cr5Ni0.5NbC形状记忆合金回复应力的影响。结果表明:(1)随着淬火温度的升高,合金的回复应力增加,在750℃左右时,合金的回复应力(加热时的最大回复应力"h和冷却到室温的回复应力"r)最大;(2)合金经1100℃×30min固溶后再进行时效处理,时效温度在450～600℃(时效时间为1h)时,合金的回复应力达到最大;时效时间(时效温度为600℃)对"h影响不大,对"r有显著的影响,当时效时间为360min时,"r达到最大,然后又降低。     

High-Temperature Oxidation Behaviour of SS 216L (Fe–16Cr–6Ni–6Mn–1.7Mo)

Oxidation behaviour of a 216L austenite stainless steel (Fe–16Cr–6Ni–6Mn–1.7Mo) was evaluated at temperature between 700 and 900?°C by thermogravimetric analysis and compared with that of SS 316L. Transmission electron microscopy in combination with energy dispersive X-ray analysis was used to study surface morphologies and chemical composition of the oxide scales formed. Replacement of Mn with Ni in SS 316L enhances its oxidation rate. SS 216L exhibits an anomalous temperature dependence of the oxidation behaviour. A kinetic inversion was observed at temperature 900?°C. Surface analysis reveals domination of Mn and iron mixed oxides in oxide scale.     

Role of Structural Factor in Elevation of Wear Resistance of a Ni – Cr – B – Si Coating after Laser Treatment

Metal Science and Heat Treatment - Metallographic studies and tests for abrasive wear resistance are performed for a Ni – Cr – B – Si coating obtained by laser powder cladding...     

Shape Memory Effect Induced by Stress-induced α' Martensite in a Metastable Fe–Cr–Ni Austenitic Stainless Steel

It is not clear whether a shape memory effect(SME) can be realized by stress-induced α' martensite in metastable austenitic stainless steels although the stress-induced ε martensite in these materials can result in the SME. To clarify this problem, the relationship between the shape recovery and the reverse transformation of the stress-induced ε and α' martensite in a 304 stainless steel was investigated. The results show that the stress-induced α' martensite can result in the SME when heating above 773 K. After deformation at 77 K and step heating or directly holding at 1073 K, two-stage shape recoveries below 440 K and above 773 K can be obtained due to the reverse transformation of the stress-induced e martensite and α' martensite, respectively. After deformation at room temperature, the α' martensite produced can result in the SME only when directly holding at 1073 K. The intrusion of more dislocations before the formation of the α' martensite at room temperature than at 77 K is the reason that the α' martensite induced at room temperature cannot result in the SME in the case of slow heating. The recovered strains resulting from the stress-induced ε and α' martensite are proportional to the amounts of their reverse transformation, respectively.     

Effect of Adding Lanthanum to Al – 5% Ti – 1% B Master Alloy on the Efficiency of Grain Refinement in Aluminum and Al – 7% Si Alloy

Metal Science and Heat Treatment - An Al – 5% Ti – 1% B master alloy with a lanthanum addition is prepared by improved technology employing halides. The effect of adding lanthanum to...     

Alloy Ti – 50.2 at.% Ni for Actuators: Evolution of Structure and Shape Memory Effects During Post-Deformation Annealing. Part 2. Influence of Structure and Phase Transformation Special Features on Shape Memory Effects

Metal Science and Heat Treatment - The first part of the paper is devoted to regular features of microstructure formation and evolution of martensitic transformations during post-deformation...     

Effects of Heat Treatment and Thermal Cycling on Martensitic Transformation Behavior of Ni59Al11Mn30 High Temperature Shape Memory Alloy

A reversible martensitic transformation (MT) takes place during cooling and heating in the solution quenched and the solution quenched plus aged Ni59Al11Mn30 alloy. The MT temperature increases with increasing solution temperature. The excellent MT characteristics can be obtained from a process of 1000℃ solution quenched plus 400℃ aged. Follow this process, the MT start temperature (Ms) and the reverse MT finish temperature (Af) are 469℃ and 548℃,respectively. The martensitic stabilization effect in the solution quenched and aged Ni59Al11Mn30 alloy is observed as an increase in the Af temperature of the first reverse MT during thermal cycles. This stabilization effect vanishes from the second thermal cycle. Thermal cycling can enhance the stability of the reversible MT. The microstructure of the quenched Ni59Al11Mn30 alloy consists of martensite (M) and gamma phase. The volume fraction of gamma phase is about 40%. The substructure of M and gamma phase is twins and dislocations, respectively. The hardness of M is higher than that of gamma phase. After aging treatment the basic phases of alloy do not change, but the hardness of the phases increases.     

Corrosion Behavior of Anodized Al Coated by Physical Vapor Deposition Method on Cu–10Al–13Mn Shape Memory Alloy

Physical vapor deposition method was utilized to apply Al coating onto Cu–10Al–13Mn alloy, then coated layer was anodized in different temperatures: 5 and 10°C as well as several potentials: 20, 30, 40, 50 V in order to achieve best anodizing parameters. The effects of anodizing parameters on alumina nanotube formation and corrosion resistance were investigated. Phase analysis on surface was conducted by X-ray diffraction method and nanotube characteristics was studied by scanning electron microscopy (SEM) and surface topology was investigated by atomic force microscopy (AFM). Additionally, the corrosion resistance of coatings was studied by potentiodynamic test in 1M NaCl solution. The results depicted that whole deposited Al layer was anodized and FCC alumina was formed merely. Polarization test results was illustrated that Al anodized layer significantly improved Cu–10Al–13Mn corrosion resistance. Uncoated specimen had highest corrosion rate and anodized layer in lower temperature and voltage had minimum alumina nanotube dimension; as a result, it had best corrosion behavior in NaCl corrosive solution.     

Effect of Nickel Alloying and Mechanical Stirring on the Microstructure and Mechanical Properties of Al – 10% Si – 5% Cu Alloy

Metal Science and Heat Treatment - The effect of nickel additions on the microstructure and ultimate tensile strength of alloy Al – 10% Si – 5% Cu in cast and heat treated conditions is...     

Effect of La and Hf Additions on the High-Temperature Oxidation Resistance of High-Purity Fe–20Cr–5Al Alloy Foils

The oxidation behavior of 30- or 50-m thick high-purityFe–20 w/o-Cr–5 w/o Al alloy foil and similar alloy foilscontaining La and La–Hf was examined in cyclic-oxidation tests at1373 and 1473 K in air. The oxidation process proceeded in three stages. Inthe first stage, an Al₂O₃ scale grew until all the Alin the foil had been removed. In the second stage, a Cr₂O₃layer grew between the Al₂O₃ layer and the substrateon the alloys containing La or La–Hf, while a (Cr, Al)₂O₃layer formed on the alloy without La and La–Hf. In the third stage,breakaway oxidation occurred. The addition of La decreased the oxidationrate in both the first and the second stages. The addition of La–Hfdecreased the rate further. The growth rate of alloys containing La orLa–Hf in the second stage was found to be proportional to thediffusion rate of oxygen in the Al₂O₃ scale. Therefore,it is inferred that the inward oxygen diffusion rate in the Al₂O₃scale on the alloy containing La–Hf was reduced compared with that onthe alloy containing La, resulting in a decrease in the oxidation rate inthe first stage.     

Effect of Casting Method on Phase Composition of Heat-Resistant Austenitic Alloys Based on the Fe – 25% Cr – 35% Ni System

Metal Science and Heat Treatment - Methods of optical and electron microscopy and x-ray spectrum microanalysis are used to study the microstructure and the phase composition of alloy HP40NbTi...