Processing and Microstructure of LaCrO3 Thin Film Derived from Chelating Precursors

Ｔｈｅｐｅｒｖｏｓｋｉｔｅ ｔｙｐｅＬａＣｒＯ3ｍａｔｅｒｉａｌｈａｓｂｅｅｎｅｘｔｅｎｓｉｖｅｌｙｉｎｖｅｓｔｉｇａｔｅｄｆｏｒｉｔｓａｐｐｌｉｃａ ｔｉｏｎ ,ｓｕｃｈａｓａｎｅｌｅｃｔｒｏｄｅｍａｔｅｒｉａｌ,ｅｌｅｃｔｒｏ ｃａｔａｌｙｓｉｓａｎｄｇａｓｓｅｎｓｏｒ[1～ 3] .Ｃｈｅｍｉｃａｌｃｏｍ ｐｏｓｉｔｉｏｎａｎｄｐｈａｓｅｐｕｒｉｔｙａｒｅｔｗｏｐａｒａｍｅｔｅｒｓｗｈｉｃｈｏｆｔｅｎａｒｅｄｉｆｆｉｃｕｌｔｔｏｂｅｃｏｎｔｒｏｌｌｅｄｉｎｍｕｌｔｉｃｏｍｐｏｎｅｎｔｍｅｔａｌｏｘｉｄｅ…     

超级双相不锈钢00Cr25Ni7Mo3.5N表面原位氧化研究

 采用高温XRD技术研究了超级双相不锈钢00Cr25Ni7Mo3.5N表面原位氧化行为。对该钢种在空气条件下进行连续加热,选取一些温度点进行测试,研究了其表面氧化物的生长规律,并分析了第二相的析出行为。结果表明, 600 ℃以下表面组织均为α、γ两相结构。800 ℃时α相开始被氧化成α Fe2O3,900 ℃时α相被氧化成α Fe2O3和Fe3O4,继续加热至1000 ℃时α相全部氧化消失。即使温度升高到1100 ℃,γ相也没有被氧化。而在空气条件下,不同温度水淬样品内部的室温组织始终保持α、γ两相结构,并且随温度增加,α相比例逐渐增加。此外,加热过程中还发现表面与内部的σ相几乎同步产生和消失。     

百米U75V钢轨矫直前冷却过程温度场的有限元分析

通过研究U75V钢轨冷却过程的热边界条件,采用三维瞬态非线性有限元法计算了百米钢轨矫直前845～150℃冷却过程的温度场。结果表明,在冷却过程中的钢轨横截面不同位置的温度下降速率不同,在冷却初期(200～2 000s),每条冷却温度线都出现一个温度降低缓和的"平台"阶段,如轨底边部冷却速度最快,开始相变时间最早;在冷却2 500～3 000s时,轨头、轨腰、轨底中心的温度迅速下降,轨头与轨底边部的温差约5℃,在冷却5 000～7 000s时,各部位温差趋于一致;计算温度值和现场实测值差别小于50℃。     

High-Temperature Mechanical Properties of Shipbuilding Steel BC in Continuous Casting

The mechanical property of shipbuilding steel BC has been studied by means of tensile test at various temperatures from 700 ℃ to 1000℃ with theGleeble-1500D thermo-mechanical simulator.The results indicate that the yield strength and tensile strength of steel have an analogous change pattern as temperature decreasing,and the transition in variation rate of strength occurs at 800℃ in both of them;the hot ductility trough of steel BC is a temperature range from 725℃ to 800℃,while the best hot ductility ranges from 875℃ to 1000℃ with the ductility value over 80%.For the sake of understanding the fracture mechanism of the steel,fracture surface and microstructure of the specimens have been examined by scanning electron microscope and metalloscope correspondingly.The results show that both the second phase particles and the pro-eutectoid ferrite surrounding the austenite boundaries play a significant role to the variation of hot ductility of steel BC.Deservedly,the research is important to the improvement and the further studies on the quality of steel during slab continuous casting process.     

316L不锈钢金属间相固溶过程中的微结构表征

利用扫描电镜、X射线衍射仪和电子背散射衍射仪等设备研究了热轧态316L不锈钢金属间相(σ相和χ相)在固溶过程中的微结构演变规律,同时,利用高温激光共聚焦显微镜对金属间相回溶的全过程进行了原位在线观察,确定了最佳固溶温度。结果表明,固溶过程中发生了γ+σ+χ→γ+σ+χ+α/FeCr→γ+α/FeCr的相变过程。金属间相的回溶从1033.1℃开始到1149.5℃结束,回溶时间为21s,消除金属间相的最佳固溶温度约为1150℃。固溶处理前,基体中分布的带状组织形态不规则,χ相和σ相的面积比分别为0.46%和0.94%;固溶处理后,带状组织形态一致,主要分布铁素体和FeCr相,而χ相和σ相不可见。     

Pb3Mn7O15:合成、相变、转换和分解

以MnO₂和PbO为原料,采用高温固相法合成Pb₃Mn₇O₁₅,采用粉末衍射、SEM和EDS技术,系统研究Pb₃Mn₇O₁₅的合成、相变、转换和分解规律.结果表明:在使用粉末合成法制备Pb₃Mn₇O₁₅时,较为合适的合成温度为850 ℃,PbO过量度为5 %.室温下Pb₃Mn₇O₁₅为正交结构,高温下为六方结构,两者在100~200 ℃之间的相变是可逆的;亚稳相Pb₄Mn₉O₂₀在800~850 ℃不可逆的分解产生Pb₃Mn₇O₁₅;Pb₃Mn₇O₁₅在950~1 000 ℃之间发生分解,分解产物为晶态Mn₃O₄和非晶态PbO.      

预处理对铜钴铁合金中钴浸出率的影响

主要研究了铜钴铁合金掺CaCO3焙烧对合金中钴浸出率的影响。合金分别添加5%、10%、15%、20%的CaCO3在900℃、1 000℃1、100℃、1 200℃、1 300℃下煅烧保温10 h,底层金属富集区与上层渣分离后破碎筛分,溶于H2SO4中。结果表明合金粉在900℃、1 000℃、1 100℃下煅烧时,钴浸出率随CaCO3添加量增加而提高;合金粉添加10%CaCO3在1 300℃下煅烧后浸出,钴浸出率达到峰值,约为95%,其后钴浸出率随CaCO3添加量增加而下降。     

Ferrite Evolution During Isothermal Process in a High Deformability Pipeline Steel

 In order to ensure the safety of long-distance oil and natural gas transmission pipeline installed in seismic and/or permafrost region, high strength pipeline steel with excellent deformability has been developed. The ferrite and bainite dual phase pipeline steel is a very important kind of high deformability pipeline steel. Polygonal ferrite is a key microstructure in ferrite and bainite dual phase deformability pipeline steel. Ferrite evolution during isothermal process at 700 ℃ after 50% deformation at 800 ℃ was conducted by using a Gleeble-3800 thermal simulator, and microstructure was characterized by using an optical microscope, a scanning electron microscope and a transmission electron microscope. There are two types of ferrite, ferrite with high density dislocation and ferrite with a little dislocation. There is about 7% (volume percent) deformation induced ferrite (DIF) for compression of 50% at 800 ℃ and strain rate of 1 s-1. During the isothermal process at 700 ℃, with the holding time increasing, ferrite volume percent, ferrite grain number and average ferrite grain size increase. As the holding time is prolonged, dislocation recovery occurs in DIF. There are secondary phases in ferrite when the holding time is too long, and secondary phases and dislocation formation in dislocation pinning.     

Influence of Solution Treatment on Microstructure of AEREX350 Alloy

The microstructure of hot rolled AEREX350 alloy under various solution treatments was investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). It was found that with increasing solution temperature,η phase precipitated firstly at grain boundaries in parallel at 800℃ and then within grains at about 980℃. The η phase precipitated at grain boundaries played a role in preventing the migration of grain boundaries,and the η phase precipitated within grains would form Widmannsttten structure with further increasing solution temperature. η phase precipitated at grain boundaries was dissolved at temperature ranging from 1080℃ to 1095℃,resulting in grain growth promptly owing to release of the pinning effect on grain boundaries. γ' phase precipitated during the process of air cooling after hot rolling and dissolved at temperature ranging between 1010℃ and 1020℃.     

3%取向硅钢中MnS沉淀析出动力学的计算

利用第二相相关理论计算分析薄板坯连铸连轧3%取向硅钢中MnS沉淀析出的动力学行为。沉淀析出计算结果显示在薄板坯连铸连轧生产工艺中以铁素体位错线上形核为主导,MnS在铁素体中的析出量最大,其有效沉淀温度范围约为700~900℃,临界形核尺寸约为0.7~1.5 nm;相变完成时MnS颗粒的半径约为30 nm,可以起到抑制剂的作用。终轧温度应在800℃以上。     

Miscibility gap due to ordering in the BCC Fe-Ge system

Phase equilibria in the bcc Fe-Ge system have been investigated by means of electron probe microanalysis and transmission electron microscopy. Two kinds of ordered phases, B2 and DO₃ types, have been detected, the B2 phase being formed from the disordered A2 phase by a 2nd order transition. The DO₃ phase is also formed from the B2 phase by a 2nd or higher order transition at higher temperatures. Below about 820 °C, however, the transition becomes a 1st order, and a miscibility gap between these ordered phases occurs in the composition range from 13 to 16 at. pct Ge. It has been also confirmed that the solubility of Ge in the bec phase shows a retrogression due to the formation of DO₃ phase. On the basis of these experimental results, the phase diagram for the Fe-Ge system has been partly revised.     

Miscibility gap due to ordering in the BCC Fe-Ge system

Phase equilibria in the bcc Fe-Ge system have been investigated by means of electron probe microanalysis and transmission electron microscopy. Two kinds of ordered phases, B2 and DO₃ types, have been detected, the B2 phase being formed from the disordered A2 phase by a 2nd order transition. The DO₃ phase is also formed from the B2 phase by a 2nd or higher order transition at higher temperatures. Below about 820 °C, however, the transition becomes a 1st order, and a miscibility gap between these ordered phases occurs in the composition range from 13 to 16 at. pct Ge. It has been also confirmed that the solubility of Ge in the bec phase shows a retrogression due to the formation of DO₃ phase. On the basis of these experimental results, the phase diagram for the Fe-Ge system has been partly revised.     

纳米AlN粉末的低温热压

研究了纳米AlN陶瓷在1 500~1 700℃的低温热压行为和力学性能.热压温度为1 600℃时,产物是β-AlN和β-Al2O3两相共存;当温度提高至1 700℃后,热压过程中出现由β-AlN到α-AlN相的转变.随着热压温度的提高,断裂形式由沿晶断裂逐渐向穿晶断裂转变,致密度逐渐提高,晶粒尺寸长大;当热压温度达到1 700℃时,相对密度为97.3%,晶粒平均直径为850nm,硬度值为15.54GPa,断裂韧度为3.5 MPa·m1/2.     

Nonequilibrium Grain Boundary Segregation of Phosphorus in Ni-Cr-Fe Superalloy

 In virtue of Auger electron spectroscopy, the grain-boundary concentrations of phosphorus in Ni-Cr-Fe superalloy after solution-treated at 1180℃ for 45 min are measured, the results show that a peak of phosphorus concentration occurs at about 180 min during isothermal ageing at 500℃, and a maximum concentration of phosphorus appears also at about 500℃ for all specimens aged for 20 min at temperatures of 200,400,500,700 and 800℃. The results are analysed with the laws of non-equilibrium grain-boundary segregation. It is found from the analysis that peaks are relative to critical time for non-equilibrium grain-boundary segregation of phosphorus.     

基于相变产物构建DP1180相变动力学方程研究

摘要：DP1180钢相变动力学方程的构建,有利于其力学性能的精准调控。利用Gleeble 3500对DP1180钢进行相变点测定,结合切线法、金相 硬度法研究了DP1180钢在冷却过程中的显微组织演变规律,绘制连续冷却转变曲线(CCT),并基于相变产物对相变动力学方程（JMAK方程）进行了修正。结果表明：冷速为0.5~1℃/s时,组织为铁素体(F)和贝氏体(B);冷速为2℃/s时,有马氏体(M)出现;冷速为10℃/s时,组织为贝氏体(B)和马氏体(M);冷速大于20℃/s时,组织以马氏体(M)为主;显微硬度随冷速的增加而升高;基于不同相变产物对n值的影响规律,对传统JMAK方程进行修正,构建了基于相变产物的相变动力学方程,预测精度得到提升。     

09MnNiDR低温容器钢高温力学性能研究

采用Gleeble-1500热模拟机研究了 09MnNiDR钢的高温力学性能,得到600～1350℃范围内试样的断面收缩率、抗拉强度和应力应变曲线,并结合扫描电镜(SEM)观察断口形貌和FactSage软件进行凝固相分析.结果表明,该钢种的第Ⅰ高温脆性区为液相线温度(tL)到1 350℃,高温塑性区为1 350～950...     

铌微合金化HRB400E高强钢筋CCT曲线测定及应用

为了研究分析铌微合金化HRB400E高强钢筋不同冷速下转变组织，达到现场精细化的生产管理的目的，利用LINSEIS L78热膨胀仪及AutoCCT软件，结合组织和硬度测定并绘制了CCT曲线。分析结果为，过冷奥氏体在冷速小于3.5 ℃/s时发生F+P转变；在冷速为3.5 ℃/s时析出B；在冷速约为20 ℃/s时无P析出，组织为B+少量F；在冷速约为32 ℃/s时发生M相变，此时无F析出；在冷速约为80 ℃/s时全部转变为M。随着冷速的增大，F晶粒逐渐变小，而硬度逐渐增大且约到80 ℃/s时趋于平缓。根据测得的CCT曲线制定现场轧制工艺为开轧温度为（1 040±30） ℃，上冷床温度为规格小于25 mm时（950±30） ℃，规格不小于25 mm时（990±30） ℃，轧后冷速为2.2~3.0 ℃/s，可得到F+P组织且性能良好的高强钢筋。     

有限元模拟在板坯直装及热装中的应用

连铸坯处在γ+α两相区装炉加热,会导致带钢心部混晶,对带钢组织及力学性能造成不利影响。以SS400钢种为例,通过有限元分析,模拟了首钢迁钢2250mm生产线紧凑型布局下连铸坯直装及热装下的温度场,并结合实际测量进行了校验。直装情况下连铸坯经切割后到达加热炉入口实际约需要15min,此时铸坯心部温度830~860℃,表面温度779~803℃,均基本处在γ+α两相区内,应予以避免。热装情况下,连铸坯下线倒坯堆冷时间应不低于2.8h,这样才能保证板坯心部温度低于700℃以完成α相变。     

温度对GH4169合金蠕变行为及机制的影响

在研究了温度对镍基高温合金GH4169蠕变行为及机制的影响基础之上,分析了其断口形貌和蠕变断裂机理。实验结果表明,随着蠕变温度的升高,GH4169合金的稳态蠕变速率逐渐升高,蠕变寿命显著降低,即该合金有极强的温度敏感性。蠕变过程中,γ″相长大聚集,并向δ相转变,随着蠕变温度的升高,γ″相向δ相转变速度加快,晶内的γ″相数量减少,δ相所占体积增加,尺寸增大,次生裂纹数量减少,尺寸减小。当蠕变温度为650 ℃时,断口中存在较多亮白色撕裂棱,韧窝尺寸大小不一,有少量析出物和碳化物;当温度提高到670 ℃时,韧窝尺寸减小,以浅韧窝为主,且出现解理面;当温度提高到690 ℃时,只存在少量韧窝,且δ相的数量显著增多,出现解理台阶,断裂方式为解理断裂或准解理断裂。      

Effect of sintering temperature on morphology and arc erosion properties of La-Ni-O ceramic and its composites

Ceramic LaNiO3 samples were prepared by solid state reaction method at different sintering temperatures. It was found that the resultant was not ABO3 perovskite single phase but dual phase La2NiO4 and NiO, and the percentage of the two phases varied with sintering temperature. Ceramics sintered at 1400 ℃ were well crystallized and the phase ratio of La2NiO4 was the maximum. The surface morphology observed by scanning electron microscopy (SEM) indicated that the grains of the ceramics sintered at 1400 ℃ were uniform and compact, which were in agreement with the properties of high density and low electrical resistivity of the samples. X-ray diffraction (XRD) patterns of ceramics before and after arc erosion indicated their high structural stability, which resulted in the good arc erosion resistance properties for silver-based electrical contact materials. The contact materials prepared with the ceramic sintered at 1400 ℃ exhibited better mass transition and arc erosion resisting properties.