phase transformation

摘要： It is the basic research subject that analyzes and calculate the law and numerical value of phase change and gas deviation coefficient of natural gas with high-CO2 content in the process of safe and effective development of gas reservoirs, which is obtained by high-pressure physical properties PVT (Pressure-Volume-Temperature) experiments and different calculation methods calculations. Aiming at natural gas with high-CO2 content in the Dongfang gas field, the phase change characteristics and physical parameters of different PVT samples are simulated and tested by Chandler 3000-GL analyzer and PVT SIM software. The experimental data shows that the phase state of natural gas with different content of CO2 has not changed in the study range. At the same time, the deviation coefficient calculated by different calculation methods (DPR, DAK, BB, HY, Gopal) are compared with the experimental data, and the applicable scope of different calculation methods are obtained. The results show that the improved Gopal has high accuracy and is suitable for the calculation of the deviation coefficient of natural gas with high-CO2 content under high temperature and high pressure in the Dongfang gas field.

摘要： Carbon neutrality of the steel industry requires the development of high-strength steel.The mechanical properties of low-alloy steel can be considerably improved at a low cost by adding a small amount of titanium(Ti)element,namely Ti microalloying,whose performance is related to Ti-contained second phase particles including inclusions and precipitates.By proper controlling the precipitation behaviors of these particles during different stages of steel manufacture,fine-grained microstructure and strong precipitation strengthening effects can be obtained in low-alloy steel.Thus,Ti microalloying can be widely applied to produce high strength steel,which can replace low strength steels heavily used in various areas currently.This article reviews the characteristics of the chemical and physical metallurgies of Ti microalloying and the effects of Ti microalloying on the phase formation,microstructural evolution,precipitation behavior of low-carbon steel during the steel making process,especially the thin slab casting and continuous rolling process and the mechanical properties of final steel products.Future development of Ti microalloying is also proposed to further promote the application of Ti microalloying technology in steel to meet the requirement of low-carbon economy.

摘要： The carbothermic reduction of vanadium titanomagnetite concentrate(VTC)with the assistance of Na_(2)CO_(3)was conducted in an argon atmosphere between 1073 and 1473 K.X-ray diffraction and scanning electron microscopy were used to investigate the phase transformations during the reaction.By investigating the reaction between VTC and Na_(2)CO_(3),it was concluded that molten Na_(2)CO_(3)broke the structure of titanomagnetite by combining with the acidic oxides(Fe_(2)O_(3),TiO_(2),Al_(2)O_(3),and SiO_(2))to form a Na-rich melt and release FeO and MgO.Therefore,Na_(2)CO_(3)accelerated the reduction rate.In addition,adding Na_(2)CO_(3)also benefited the agglomeration of iron particles and the slag–metal separation by decreasing the viscosity of the slag.Thus,Na_(2)CO_(3)assisted carbothermic reduction is a promising method for treating VTC at low temperatures.

摘要： ZrO_(2)-YO_(1.5)-TaO_(2.5)(ZYTO)is a promising top-coat material for thermal barrier coatings(TBCs).The bulk properties of ZYTO have been reported by several studies,but its performances as TBCs are less-well understood.In this work,ZYTO TBCs were prepared by air plasma spraying(APS)and their thermal cycling performances were investigated at 1150°C.Despite of the good bulk properties,APS ZYTO TBCs present an extremely short thermal fatigue life.This is attributed to the non-equilibrium grain-boundary segregation of TaO2.5 induced by limited solubility and rapid quenching during APS process,resulting in a tetragonal(t)to cubic(c)and metastable-tetragonal(tm)phase transformation in ZYTO TBCs.The volume shrinkage(~0.74vol%)of phase transformation leads to many cracks at the c/tm phase boundaries after deposition.On the other hand,the formation of cubic phase with massive grain-boundary Ta segregation induces a large intergranular embrittlement and a weak bonding strength(~5.3 MPa),resulting in the premature failure of the ZYTO TBCs.

摘要： In this paper, the effect of hot-rolling processing parameters on the post-rolling transformation behavior of C-Mn-Cr-Cu weather-resistant martensitic steel was investigated.Results indicate that the post-rolling transformation behavior, particularly the post-coiling transformation behavior, strongly depends on the coiling temperature.Under a high coiling temperature, ferrite/pearlite transformation was mainly observed with a low trans-formation speed and transformation dilation after coiling.With decreasing coiling temperature, the proportion of bainite transformation increased with an increased transformation speed and transformation dilation.The dependence of transformation behavior on the coiling temperature could be one of the most important reasons behind the coil collapse of the experimental steel.The optimization of hot-rolling and coiling processing parameters of the steel strip, including laminar flow cooling, coiling temperature, and suspension time on the winding machine, can signi-ficantly reduce the transformation dilation of the steel after hot rolling, thus effectively controlling the coil collapse of the steel.

摘要： The article presents our generalization of electron microscopy results that got for binary and some ternary alloys based on Ni. These results are considered as the basis for the conclusion that chemical bonds between atoms are realized in binary alloys according to the principle of pair-wise chemical interaction. In ternary alloys, such a process begins with the separation of the liquid alloy into diffusion micro-pairs, inside which particles of a new phase are subsequently formed. The latter circumstance allows us to consider the liquid state of the alloy as the initial stage of the formation of a new phase. That formation of diffusion micro-pairs (and particles of a new phase inside them) occurs because of the presence of alloys, along with a metallic bond, of the ionic and covalent components of a strong chemical bond, which exist at all temperatures of the condensed state. The article shows what exactly needs to be done so that such a branch of science as the science of alloys can get rid of the empirical approach when creating new alloys.

摘要： This work presents mechanical properties of the NiTi polycrystalline superelastic shape memory alloys(SMA) of 5 different grain sizes under high-speed impacts. The amorphous, nanocrystalline(40, 80, 120 nm) and coarse grain(20 μm) sheets are manufactured with cold rolling and suitable heat treatments. A Hopkinson tensile bar is used to perform tests up to 45 m/s. Highspeed camera system and digital image correlation method are used to get the strain field and particle velocity field at a sampling frequency of 2×10~6 frames/s with a resolution of 924×768 pixels. Nominal stress-strain curves are obtained for all the sheets with a strain rate of about 1000 s~(-1) and they have a similar evolution to the quasi-static case but with much higher stress levels. The rate sensitivity is increased with the grain size and the stress level can reach up to a 70% growth for a coarse grain sheet but be totally insensitive for the amorphous sheet in the strain rate from 10~(-4) to 10~3 s~(-1). A single transformation front can be found under high-speed impact(45 m/s) at the early loading stage. The speed of the transformation front is calculated from strain time histories and the highest front speed of 811 m/s is observed which is never observed before. It also reveals that the front speed depends also on the grain size. With the same loading speed, the bigger the grain size is, the slower the transformation front speed is.

摘要： It is well-known that the surface quality of the niobium microalloy profiled billet directly affects the comprehensive mechanical properties of the H-beam.The effects of chromium on theγ/αphase transformation and high-temperature mechanical properties of Nb-microalloyed steel were studied by Gleeble tensile and high-temperature in-situ observation experiments.Results indicated that the starting temperature of the γ→αphase transformation decreases with increasing Cr content.The hot ductility of Nb-microalloyed steel is improved by adding 0.12wt% Cr.Chromium atoms inhibit the diffusion of carbon atoms,which reduces the thickness of grain boundary ferrite.The number fractions of high-angle grain boundaries increase with increasing chromium content.In particular,the proportion is up to 48.7% when the Cr content is 0.12wt%.The high-angle grain boundaries hinder the crack propagation and improve the ductility of Nb-microalloyed steel.

摘要： Due to the quantum confinement effect,atomically thin two-dimensional(2D)monolayer materials possess distinct characteristics from their corresponding bulk materials,which have received wide attention from science and industry.Among all the 2D materials,elemental 2D materials with the simplest components are most striking.As an emerging group-VIA elemental 2D monolayer material,tellurene exhibits many exciting fundamental properties,such as chemical and mechanical stabilities,bandgap and high carrier mobilities compared to phosphorene,graphene and MoS2,respectively.Besides,in further exploration,it was found that tellurene or tellurene-based device presents excellent thermoelectric properties,piezoelectric properties,quantum Hall effects,and superb optical properties especially nonlinear optics characteristics,etc.The properties of tellurene can be modulated by virtue of strain,defects,edges,and heterojunction effects.In view of so many unique properties,it has drawn significant interest since tellurene was predicted and fabricated successfully in 2017.In this paper,we review the 2D tellurene allotropes,experimental preparation,excellent properties,performance modulation and future development.

摘要： The shape memory effect and nanoindentation response of various phases of sputtered NiTi shape memory thin films were investigated as a function of temperature.The phase transformation temperatures of NiTi films were observed to be sensitive to a compositional shift.The mechanical properties of NiTi thin films also presented a significant response to phase transformations.At the same load,the maximum indentation depth for austenite is smaller than for martensite,indicating that martensite is softer than austenite.A martensite thin film was converted to austenite via in situ heating nanoindentation and displayed the mechanical properties similar to the austenite film at room temperature.These results underscore the validity of elevated temperature nanoindentation methods as a means of interrogating the mechanical properties of materials that undergo thermally-induced phase transformations.The details of the load–displacement curves are also described.

摘要： To investigate the iron oxidization function in CaO-FeOx-SiO2 slag, gas was injecting into molten so as to oxidize it. The variation of the iron valence states with the oxidizing time in different temperature was obtained by chemical analysis method. Microstructure of slag was observed by metallographic microscope and SEM, and phases composition ascertained by EDX and XRD. The regularity of the phases transformation and the oxidizing kinetic equations of the iron were obtained, which provide a theoretical base for compressively utilizing of the slag.

摘要： To investigate the iron oxidization function in CaO-FeOx-SiO2 slag, gas was injecting into molten so as to oxidize it. The variation of the iron valence states with the oxidizing time in different temperature was obtained by chemical analysis method. Microstructure of slag was observed by metallographic microscope and SEM, and phases composition ascertained by EDX and XRD. The regularity of the phases transformation and the oxidizing kinetic equations of the iron were obtained, which provide a theoretical base for compressively utilizing of the slag.

摘要： To investigate the iron oxidization function in CaO-FeOx-SiO2 slag, gas was injecting into molten so as to oxidize it. The variation of the iron valence states with the oxidizing time in different temperature was obtained by chemical analysis method. Microstructure of slag was observed by metallographic microscope and SEM, and phases composition ascertained by EDX and XRD. The regularity of the phases transformation and the oxidizing kinetic equations of the iron were obtained, which provide a theoretical base for compressively utilizing of the slag.

摘要： To investigate the iron oxidization function in CaO-FeOx-SiO2 slag, gas was injecting into molten so as to oxidize it. The variation of the iron valence states with the oxidizing time in different temperature was obtained by chemical analysis method. Microstructure of slag was observed by metallographic microscope and SEM, and phases composition ascertained by EDX and XRD. The regularity of the phases transformation and the oxidizing kinetic equations of the iron were obtained, which provide a theoretical base for compressively utilizing of the slag.

摘要： To investigate the iron oxidization function in CaO-FeOx-SiO2 slag, gas was injecting into molten so as to oxidize it. The variation of the iron valence states with the oxidizing time in different temperature was obtained by chemical analysis method. Microstructure of slag was observed by metallographic microscope and SEM, and phases composition ascertained by EDX and XRD. The regularity of the phases transformation and the oxidizing kinetic equations of the iron were obtained, which provide a theoretical base for compressively utilizing of the slag.

摘要： To investigate the iron oxidization function in CaO-FeOx-SiO2 slag, gas was injecting into molten so as to oxidize it. The variation of the iron valence states with the oxidizing time in different temperature was obtained by chemical analysis method. Microstructure of slag was observed by metallographic microscope and SEM, and phases composition ascertained by EDX and XRD. The regularity of the phases transformation and the oxidizing kinetic equations of the iron were obtained, which provide a theoretical base for compressively utilizing of the slag.