Fe_3Al和FeAl合金的高温氧化行为

研究了含Nb、Nb和Cr的Fe_3Al合金,含Zr的FeAl合金在1050℃的氧化行为。结果表明Fe_3Al和FeAl合金氧化增重均符合抛物线规律。对于Fe_3Al合金,氧化层由Al_2O_3和Fe_2O_3组成;加入少量Nb,增加了氧化层的粘附性,从而改善合金的抗氧化性。对FeAl合金,氧化层为Al_2O_3;Zr的加入,虽然引起合金的内氧化,但却提高Al_2O_3的粘附性。     

EFFECT OF Ce AND Cr ON ROOM TEMPERATURE MECHANICAL PROPERTIES OF Fe_3Al

Small amount addition of Ce to Fe_3Al results in a significant increase of room temperaturestrength of the alloy,and the combined addition of Ce and Cr improves both strength andductility.The fracture mode of Fe_3Al containing Ce is a mixed one of approximately 70%transgranular cleavage and 30% intergranular failure.In the deformed specimens of binaryFe_3Al the dislocations observed are mainly single dislocations with =(1/4)a_0~'〈111〉.However,a number of superlattice dislocations can be observed in the deformed specimens ofthe alloys with Cr addition.     

EFFECT OF ALLOYING ELEMENT ON MECHANICAL PROPERTIES OF Fe_3 AL AND FeAI ALLOYS

The effect of alloying element such as Mo,Si or B and its stoichoimetric composition on thetensile properties at room and elevated temperatures,and also on the microstructure of Fe_3Aland FeAl alloys has been investigated.Two Fe aluminides were found to be obviouslystrengthened by all of three elements,but seriously embrittled by Mo and Si.An improvemenover the plasicity of FeAl may be made by adding B,and the fracture surface is variedfromintergranular to transgranular cleavage type.The room temperature plasticity of the Fe-richFe_3Al or Al-rich FeAl is much better than that of the stoichoimetric aluminides.An anoma-lous temperature dependence on the yield strength of Fe_3Al in range of 400 to 500℃ or ofFeAl in range of 400 to 500℃ was found.Discussion has been carried out by the aspect ofmicrostructure.     

中高温时效处理对Cr21铁素体不锈钢组织和性能的影响

采用光学显微镜、扫描电子显微镜和透射电镜并通过硬度和冲击实验,研究了Cr21铁素体不锈钢经固溶+时效处理后的显微组织和性能。结果表明:Cr21铁素体不锈钢经600、650℃和750℃时效处理50 h内均未形成sigma相以及铬的碳化物,主要析出了大量的TiC、NbC和(Ti,Nb)C复合粒子以及少量的Fe2Nb(Laves相)。在600、650℃时效处理50 h内,钢的硬度基本是先升高后降低,韧性先降低后升高。而750℃时效时则硬度几乎一直升高,韧性一直降低。     

INFLUENCE OF COLD-WORKING AND HEAT TREATING ON ELASTIC PROPERTIES OF Nb AND Nb-BASE ALLOYS

The elastic limit of single-phase alloy Nb-2Mo-2Zr-1Ti is higher as recovered state incomparison with as cold-rolled or recrystallized one.For Nb-40Ti-5.5AI alloy ofage-hardening type,the elastic limit is lower as cold-rolled state,but increases considerablyafter proper aging.However,its elastic modulus changes no more,so the stored-energy(σ_e~2/E)may raise significantly.The temperature dependence on elastic modulus for pureNb as intensely cold-worked or recrystallized state is anomalous.This anomaly may disap-pear after recovered treatment of intensely cold-worked state at 600℃ for 4 h.and maychange no more after that of recrystallized state.The anomalous behaviour of elasticity wasalso discussed on the non-magnetic Nb.     

EFFECT OF Nb ON STRENGTHENING OF Fe-BASE SUPERALLOY AT INTERMEDIATE HIGH TEMPERATURES

Because Nb accelerates the uniform distribution of MC phase and the grain refinement,aswell as,increases the amount and stability of γ-phase,the tensile strength,ductility,stressrupture life and fatigue limit of Fe-30Ni-13Cr-1.2W-1.5Mo-2.5Ti-0.4AI superalloy at650℃ can be improved with increase of Nb content up to 1.22 wt-%.The precipitation ofsmall Laves phase particles dispersed along grain boundaries may be favourable to combinedproperties of the superalloy containing 1.22 wt-% Nb.It will be worsened only that the pre-cipitation of Laves phase particles'dispersed along grain boundaries may be favourable forcombined properties of the superalloy containing 1.22 wt-% Nb.It will be worsened onlythat the precipitation of Laves phase is too more because of too high Nb content existhing.     

水蒸汽含量对SA213T91钢650 ℃氧化行为的影响

研究了ASME213 T91钢(T91钢)650℃下在(Ar+H2O)气氛中不同含量的水蒸汽中的高温氧化行为.T91钢在5%、7%和10%Ar+H2O气氛中氧化10 h的氧化动力学曲线表明,在含5%H2O气氛中氧化时,动力学符合抛物线规律,在其余两种浓度下氧化遵从分阶段抛物线规律.随水蒸汽含量的增大,氧化速度明显增大.在T91钢表面形成了多层结构的氧化膜.氧化膜组成从外到内依次为Fe2O3,Fe3O4和(Fe,Cr)3O4.探讨了不同含量的水蒸汽对T91钢氧化行为的影响机理     

EFFECT OF Nb ADDITION ON MICROSTRUCTURE OF(Nd,Dy)-(Fe,Co)-B MAGNETS

An addition of Nb up to 2 at.-% into(Nd,Dy)-(Fe,Co)-B alloy causes the formation ofdendrite Fe_2Nb and the precipitates in hard magnetic grains.Both increases withincreasing Nb content.During sintering,part of Fe_2Nb dissolves within the 2:14:1 grains,and the Fe_2Nb along grain boundaries hinders the growth of 2:14:1 grains.During an-nealing,the dissolved Nb in(?)-phase precipitates out,and this nearby the grain boundarydiffuses into Nd-rich phase to form new granular Fe_2Nb and to increase the Nb contentin Nd-rich phase,this results in a precipitate-free zone in the(?)-grain near Nd-rich phase.     

Fe3Al基金属间化合物合金强韧化途径探索

通过多元合金化成分控制及热机械处理工艺优化,Fe_3Al基金属间化合物合金的室温力学性能得到较大幅度的全面提高延伸率由铸态下的2—3％上升到15—20％,屈服强度达到500MPa左右研究表明:片状晶粒、B_2结构及第二相弥散粒子有利于室温性能的全面改善     

CHANGE OF BORIDE IN Fe_(70)Cr_(18)Mo_2SiB_9 WITH THERMAL TREATMENT

The formation of borides M_3B_2 M_2B_2 and M_(23)B_6 may be carried out from the melt-quenchedFe_(70)Cr_(18)Mo_2SiB_9 during 700—1150℃ annealing.As the temperature raising,the M_2B,themajority being Fe_2B.may be gradually replaced by Cr_2B via the co-existence between Fe_2Band Cr_2B.The Cr_2B may be formed by trans formation of Fe_2B through the atomic substitu-tion and structural adjustment.The thin slice of remaining Fe_2B is sandwiched between(100)faces of(Cr,Fe)_2B as stacking fault.The M_2B_2 is virtually composed of theMo_(1+x)(Fe,Cr)_(2-x)B_2 where x(0≤x≤1)increases with the increase of temperature.     

RELATIONSHIP BETWEEN CREEP PROPERTIES AND STRUCTURE OF STEEL 20Cr11MoVNbNB

Studies were made of the creep properties and structure change of steet 20Cr11MoVNbNB at550-650℃.It is found that at 550℃ when creep stress>180 MPa there exists linear rela-tion with two different slopes β_1 and β-2 between transitional creep strain ε_β and creeptime t~(1/3),and β_1(in initiol period)>β_2(in later period).The Creep rate of stable stage at550℃ can be expressed by =Aσ exp(-Q_ /RT),where,n=4.7.A exp(-Q_ /RT)=5.37×10~(-16).Apparent creep activation energy Q_ =430 kJ/mol at 550-650℃,which ismuch higher than the self-diffusion activation energy of atoms for matrix Fe.In creepprocess,as the creep stress and time increase,the total weight of precipitated phases and rela-tive weight of Cr,Mo and V increase,but those of Fe and Nb decrease in precipitated phases,     

Co-Ni型超高强度钢的微观组织结构与力学性能

利用透射电镜、扫描电镜等试验手段研究了回火温度对2000 MPa和2200 MPa两种强度级别Co-Ni超高强度钢的微观结构、断口形貌与力学性能的影响。结果表明,两种强度级别Co-Ni超高强度钢的强化均与M2C碳化物有关。Co-Ni超高强度钢在400~450℃回火韧性出现谷值,产生的原因与板条边界存在Fe3C、M3C及M2C处于共格状态,使马氏体基体产生强烈静畸变有关,冲击试样断口微观形貌表现为准解理断裂。Co-Ni超高强度钢在480~510℃回火,马氏体板条内析出细小、弥散的M2C,粗大片状Fe3C被细小、弥散的MC取代,使其具有比较好的强韧性配合。     

表面涂少量氧化锰提高Ti47Al2Cr2Nb合金高温抗氧化性

研究了表面涂少量MnCl2对Ti47Al2Cr2Nb合金900℃恒温氧化行为的影响。涂少量MnCl2后合金的氧化速率降低了50%以上,氧化膜也由TiO2和Al2O3的混合物变为以Al2O3为主的氧化物。发生上述变化的原因可能在于氧化开始时合金中钛与Cl反应形成钛的亚稳态氯化物挥发掉,合金表面形成一层致密的氧化铝膜,阻碍合金中的Ti向外扩散氧化,因此提高了合金的高温氧化性能。     

镍和铌元素对Cr5冷轧辊工作层组织和性能的影响

研究了0%-0.4%Ni和0%-0.05%Nb对Cr5冷轧辊钢组织和性能的影响.结果表明,钢中添加Ni元素可以细化组织,随着Ni含量的增加,冷轧辊钢的淬透性、硬度和耐磨性都得到一定程度的提高,含有0.2%Ni的轧辊硬度和耐磨性提高得比较显著;钢中的Nb元素以碳化物的形式存在,能阻止晶粒长大,提高了冷轧辊钢的硬度和耐磨性...     

EFFECT OF Cr,Cu AND Co ON MAGNETOSTRICTION OF Fe-Si-B AMORPHOUS ALLOYS

The dependence of composition varied,especially C,Si,Cr,Cu and Co in four amorphousalloy systems Fe_(80-x)Cr_xSi_5B_(15).Fe_(80-x)Cr_xC_5B_(15).Fe_(80-x)Cu_xSi_5B_(15)and(Fe_(1-x)Co_x)_(82)Cu_(0.4)Si_(4.4)B_(13.2)upon their saturation magnetostriction at room temperature hasbeen studied.It was observed that the saturation magnetostriction of the alloys may be re-markably improved by small addition of Cu and Co.the peak value being up to 70×10~(-6)asx=0.02 in alloys(Fe_(1-x)Co_x)_(82)Cu_(0.4)Si_(4.4)B_(13.2).     

THREE-DIMENSIONAL TOPOLOGICAL ANALYSIS OF Nd-Fe-B AND Pr-Fe-B PHASE DIAGRAMS

With the aid of 3-dimensional topological analysis methodology,relationships amongphage regions on the isothermal section of the Nd-Fe-B phase diagram at 1000℃ andthose on vertical sections of the Pr-Fe-B phase diagram passing through Pr_2 Fe_(14)B pointhave been re-discussed and modified.     

固溶处理冷却速率对ZG0Cr17Ni4Cu4Nb钢性能的影响

研究了固溶处理冷却速率对ZG0Cr17Ni4Cu4Nb钢时效后力学性能的影响。固溶处理温度为1040℃和1050℃,冷却方式为空冷、水冷和油冷;时效温度分别为470℃、480℃、490℃、500℃和550℃。结果表明,固溶处理后的冷却速率对ZG0Cr17Ni4Cu4Nb钢力学性能的影响很大,最佳热处理工艺为1040℃保温50 min,油冷,然后490℃时效3 h空冷,再于470℃时效4 h空冷。     

几种钢材渗Al涂层在海水淬冷时的循环氧化研究

对4种不同级别的钢在600℃～800℃氧化和海水淬冷 交替作用下的循环腐蚀行为进行了研究.在实验条件下,绝大多数材料均发生了严重的氧化 .特别在800℃下,所有材料氧化失重明显.材料施加渗Al涂层后,极大地改善了它们的抗 氧化性能,且材料级别越低,改善作用越明显.海水中的NaCl对材料的高温腐蚀有显著的加 速作用,造成渗Al涂层快速退化.循环淬冷造成渗Al涂层外层发生开裂,且在蒸馏水中比在 海水中淬冷时形成的裂纹数量多且宽度大.     

Cr,Cu,Co对Fe—Si—B非晶合金磁致伸缩系数的影响

本文报道了Fe_(80-x)Cr_xSi_5B_(15),Fe_(80-x)Cr_xC_5B_(15),Fe_(80-x)Cu_xSi_5B_(15)和(Fe_(1-x)Co_x)_(32)Cu_(0.4)Si_(4.4)B_(13.2)四系列非晶合金在室温下的饱和磁致伸缩系数λs随成分x的变化关系,讨论了C,Si,Cr,Cu,Co原子对磁致伸缩系数的影响。发现少量Cu,Co的加入大大提高了非晶合金的λs。特别是(Fe_(1-x)Co_x)_(82)Cu_(0.4)Si_(4.4)B_(13.2)系列中当x=0.02时峰值λs=70×10~(-6)。     

核反应堆用FeCrAl合金板材的试制及其组织性能研究

在对Fe13Cr5AlxNb合金熔炼、锻造、轧制等制备工艺研究的基础上,利用光学显微镜、透射电镜、扫描电镜以及电子背散射衍射研究了合金板材的微观组织演化特征。研究了不同热处理温度（800、850、900、1 000 ℃）下合金板材中第二相的析出特点及对其力学性能的影响规律。结果表明,合金板材在800 ℃保温5~25 h后,其室温力学性能稳定;合金板材在800~1 000 ℃、20 h高温时效后,在800~850 ℃时,其强度稍有降低,而在900~1 000 ℃时,其强度随温度的升高而提升。同时,对不同Nb含量的合金板材常温和高温力学性能进行了测试,Nb质量分数为1.0%~1.5%时,合金板材具有良好的力学性能。