Advances in the research of nitrogen containing stainless steels

The current status of nitrogen containing stainless steels at home and aboard has been introduced. The function and existing forms of nitrogen in the stainless steels, influence of nitrogen on mechanical properties and anti-corrosion properties as well as the application of nitrogen containing cast stainless steels were discussed in this paper. It is clear that nitrogen will be a potential and important alloying element in stainless steels. And Argon Oxygen Decarbonization (AOD) refining can provide an advanced manufacture process for nitrogen containing stainless steels with ultra-low- carbon and high cleanliness.     

Solid-solution hardening and softening by Fe additions to NiAl

Solid-solution hardening in the case of a ternary alloy addition to a B2 compound with the triple defect structure has been investigated. The fact that the ternary element may occupy either of two sublattices or may affect the concentration of other types of point defects present in the material makes this a very interesting problem to consider. Ni-rich (40 at% Al), stoichiometric (50 at% Al), and Al-rich (52 at% Al) alloys were doped with up to 12 at% Fe. Lattice parameter, bulk density and hardness measurements were performed on samples quenched from 1000 °C. It was found that solid-solution softening actually occurs in the Ni-rich alloys, while hardening was observed in the stoichiometric and Al-rich alloys. The vacancy concentration was determined from the experimental data, and the site occupancies of the Fe atoms were estimated from a thermodynamic model. Through careful consideration of all point defect concentrations the solid-solution hardening and softening behaviors could be effectively rationalized.     

低铬X70管线钢组织及其抗CO2

为了明确Cr的质量分数高低对埋地用输油输气管线钢性能的影响,设计了4种Cr的质量分数的X70管线钢,研究了不同Cr的质量分数下管线钢组织及其力学性能,并采用高温高压反应釜进行了实验钢的CO₂腐蚀试验.结果表明：钢中加入0.1%~0.8%的Cr后,其组织均由针状铁素体和准多边形铁素体构成,Cr元素均呈现明显的沿晶界分布状态;随着Cr的质量分数的增加,钢板强度随之升高,晶界中Cr分布密度随之增大,Cr（OH）₃在腐蚀产物膜中的富集量增加,促使钢板的平均腐蚀速率降低;同时由于Cr（OH）₃可以有效阻碍阴离子穿透腐蚀产物膜,因而大大减少了Cl-的催化作用导致的点蚀,使得钢板点蚀速率明显降低.     

Spray pyrolysis deposition of Cu–Zn–In–S solid-solution thin films with tunable compositions and band gaps

Cu–Zn–In–S solid solution thin films with tunable compositions and band gaps were deposited on glass substrates using a chemical spray pyrolysis approach. XRD results reveal the cubic-structured Cu–Zn–In–S films without detectable impurities. The successive shift of XRD patterns toward high-angle side of ZnS with increasing ZnS molar fraction in products proves a formation of Cu–Zn–In–S solid solutions. SEM images and EDAX analyses demonstrate homogeneous surface morphologies and adjustable compositions of Cu–Zn–In–S films, which results in film band gaps broadly tunable from 1.54 eV to 3.61 eV. These sprayed Cu–Zn–In–S solid solution thin films may find potential uses in photovoltaics and photocatalysis.     

稀土元素对ZM5镁合金性能的影响

研究添加富铈混合稀土的ZM5合金在铸态和固溶处理后的显微组织与力学性能。结果表明,添加适量的混合稀土能显著提高ZM5合金强度，合适的RE添加量对铸态合金为1．5％，固溶处理合金合为0.75％。周溶处理使未添加稀土的ZM5合金偏析产生的晶界沉积相（β-Mg17Al12）和含Mn的中间相（Al6Mn，Al4Mn）溶解而改善合金的塑性。对添加稀土的ZM5合金，固溶处理不仅使β-Mg17Al12相溶解。还使粗大棒状的Al41RE3熔断而细化、球化，从而显著提高合金的强度和塑性。     

喷射成形Al-Zn-Mg-Cu合金的显微组织演变

采用喷射成形技术制备了高Zn含量的超高强度Al-12．40Zn-2．68Mg-2．40Cu合金(质量分数，％)．对合金进行热挤压，在不同固溶温度和时间下对挤压合金进行固溶处理，并进行力学性能测试．结果表明：随着固溶温度的升高及固溶时间的延长，第二相富Cu颗粒随之相应溶解，再结晶晶粒合并与长大；当固溶温度达到490℃时，富Cu颗粒相基本溶解，合金完全再结晶．合金进行T6热处理后，抗拉强度达到800MPa以上，延伸率为7．5％．     

固溶冷却方式对AM50镁合金组织和耐蚀性能的影响

通过XRD、SEM、EDS、电化学腐蚀测试,研究了铸造AM50镁合金固溶后水冷和炉冷两种处理方式对组织及耐蚀性能的影响。结果表明,固溶处理后,由于大量Al固溶进α-Mg中,两种方式冷却的AM50镁合金相组成主要为α-Mg、Al₆Mn和少量β-Mg₁₇Al₁₂。由于冷却速率的不同,炉冷样比水冷样的β-Mg₁₇Al₁₂的数量多,体积大,并且围绕Al₆Mn相析出,而且大多在晶界处析出。由极化曲线和腐蚀速率曲线可以看出炉冷样的腐蚀速率较高,耐蚀性较差。由于β-Mg₁₇Al₁₂数量的增加以及α-Mg相中固溶Al的数量减少,导致炉冷试样比水冷试样的腐蚀速率高,而且经过168 h腐蚀形成了蚀坑带。     

冷轧与时效工艺对2205双相不锈钢σ相析出的影响

对1050 ℃固溶处理后的2205双相不锈钢在650~1000 ℃下时效处理,利用金相显微镜(OM)和扫描电镜(SEM)观测不同工艺条件下σ相析出规律,绘制了σ相析出TTP曲线图,描述了σ相析出特征。结果表明:时效初期,σ相优先在铁素体与奥氏体相界处形核,随着时效温度的升高和时效时间的增加,σ相不断长大、粗化并向铁素体基体内延伸;时效时间越长,析出相越多,时效时间相同时,当温度达到850 ℃,析出量达到最大值,之后随着温度的升高而降低。σ相析出温度范围为650~950 ℃,析出鼻尖温度为850 ℃,轧制变形量增加,σ相析出速度加快,但并不影响其析出的鼻尖温度。     

添加Sb2O3对NBT基陶瓷介电和铁电性能的影响

采用传统电子陶瓷的制备工艺,制备出微量BiSbO3固溶的(Na0.5Bi0.5)TiO3(NBT-xBS,x=0~0.03)陶瓷,并对其结构、介电及铁电性能进行了研究。X-射线衍射分析结果表明四种配方均形成了钙钛矿结构晶相。扫描电镜分析显示BiSbO3的引入有助于烧结形成致密的多晶结构。随着BiSbO3固溶量的增加,样品的介电常数减小,而介电损耗基本不变,陶瓷的弛豫性增强,是由于BiSbO3的引入使得晶体结构中A和B位离子排列更加无序造成的。BiSbO3的固溶使NBT仍保持较高的极化强度,矫顽场从7.3 kV/mm降至4 kV/mm,从而在一定程度有效解决了NBT高矫顽场的问题。     

Possibilities for high-temperature strengthening in iron aluminides

Iron aluminides based on Fe₃Al and on FeAl offer considerable possibilities for development as intermediate temperature materials operating in aggressive chemical environments. Two major property limitations restrict their application: low toughness, related to their environmental sensitivity, and poor high temperature creep resistance. Considerable attention has been given to the intermediate stress but, while many of its characteristics are well documented, there remains considerable uncertainty about the controlling mechanisms. Plastic deformation at temperatures above the stress peak can be analysed in terms of thermally-activated, creep-like flow, with a steady evolution during deformation of many of the controlling parameters. Two avenues can be explored for improving high temperature behaviour: modify the diffusive flow behaviour and restrict dislocation motion at dispersed particles. There is considerable evidence that control of matrix composition can lead to large changes in diffusion parameters and the motion of dislocations. Dislocation pinning at particles depends on the availability of suitable particle phases, and examples of precipitated carbides, dispersed oxides, and decomposed intermetallic mixtures will be considered.