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Journal of Materials Science & technology 2004年第5期20卷 561-566页

作者： RuihengWU XueyuRUAN HongbingZHANG t.y.hsu DepartmentofPlasticitytechnology ShanghaiJiaoTongUniversityShanghai200030China Departmentof.MaterialsEngineering ShanghaiInstituteofTechnologyShanghai200233China SchoolofMaterialsScieuceaudEugineering ShanghaiJiaoTougUuiversityShanghai200030China

By combining the α/γ interface migration and the carbon diffusion at the interface in Fe-C alloys, a mathematical model is constructed to describe the mixed-control mechanism for proeutectoid ferrite formation from austenite. In this model, the α/γ interface is treated as non-equilibrium interface, i.e., the carbon concentration of austenite at γ/α interface is obtained through theoretical calculation, instead of that assumed as the local equilibrium concentration. For isothermal precipitation of ferrite in Fe-C alloys, the calculated results show that the rate of interface migration decreases monotonically during the whole process, while the rate of carbon diffusion from γ/α interface into austenite increases to a peak value and then decreases. the process of ferrite growth may be considered as composed of three stages: the period of rapid growth, slow growth and finishing stage. the results also show that the carbon concentration of austenite at γ/α interface could not reach the thermodynamic equilibrium value even at the last stage of ferrite growth.

关键词： Proeutectoid ferrite precipitation Non-equilibrium interface Phase transformation kinetics Mixed-control mechanism

X-ray Peak-Shift Determination of Deformation Fault Probability in Fe-Mn-Si Alloys

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Journal of Materials Science & technology 2002年第5期18卷 459-461页

作者： yonghuaRONG GangHE ZhenghongGUO ShipuCHEN t.y.hsu(XUZuyao) Sch. of Mat. Sci. and Eng. Shanghai Jiaotong Univ. Shanghai 200030 China

the X-ray diffraction peak-shift method was introduced into the determination of deformation fault probability (a) of Fe-Mn-Si alloys with various Mn contents and thermomechanical cycling numbers. the precise lattice constants required were obtained by numerical calculation instead of using standard sample without any fault. the influence of internal stress on the determined a has been evaluated, and the caused relative error was determined as about 4% and thus negligible. the results show that the deformation fault probability increases with decreasing Mn-content and increasing cycle number, which are qualitatively consistent with those results of Psf determined by peak-broadening method.

关键词： X-ray diffraction Peak-shift method Deformation fault probability Fe-Mn-Si alloy

Effect of Rare Earth Elements on Isothermal transformation and Microstructures in 20Mn Steel

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Journal of Rare Earths 1992年第3期10卷 189-194页

作者：刘和郑登慧 t.y.hsu徐祖耀 Department of Materials Science Jiao Tong UniversityShanghai 200030China

the effect of rare earth elements on the isothermal transformation and microstructures in 20Mn steel is in- vestigated by means of metallography and *** earth elements decrease both the incubation period of pro-eutectoid ferrite and the rate of pearlitic *** addition,rare earth elements play a role of reducing needle-like ferrite and the amount of pearlite,densifing the lamellar space of pearlite and enhcing segregation of carbide in granular *** is suggested that rare earth elements may decrease the interfacial energy of grain boundary and interphase,hinder the diffusion of carbon atoms and form rare earth carbides with high melting point which reduce the carbon content in austenite.

关键词： Mixed rare earths Isothermal transformation Microstructures of 20Mn steel

tHERMODyNAMICS OF MARtENSItIC tRANSFORMAtION IN β-Cu BASE ALLOyS

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Acta Metallurgica Sinica(English Letters) 1991年第6期4卷 401-406页

作者： t.y.hsu Department of Materials Science Shanghai Jiaotong UniversityShanghaiChina

An approach for the thermodynamics of the thermoelastic martensitic transformation in β-Cu base alloys is *** forces for martensitic transformation,t_0 and M_s tempera- tures in Cu-Zn,Cu-Al and Cu-Zn-Al alloys were calculated and the calculated M_s are in good agreement with the experimental *** of the parent phase lowers M_s(t_0)in Cu-Zn and Cu-Zn-Al alloys,but raises M_s(t_0)in Cu-Al *** methods for the es- timation of the critical driving force for the thermoelastic martensitic transformation are also introduced.

关键词： β-Cu base alloy martensitic transformation thermodynamics

SOME ASPECtS OF PROGRESS AND PERSPECtIVE IN MARtENSItIC tRANSFORMAtION

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Acta Metallurgica Sinica(English Letters) 1991年第6期4卷 387-400页

作者： t.y.hsu Shanghai Jiaotong University ShanghaiChina

Progress and perspective in martensitic transformations are described,including the definition and the thermodynamics of martensitic transformatian,the effect of austenite state on martensitic transformation,kinetics,... 详细信息

关键词： martensitic transformation

tHEOREtICAL PREDICtION OF tHE KINEtICS CURVES OFPEARLItIC tRANSFORMAtION IN HyPO-PROEUtECtOID StRUCtURAL StEELS

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Acta Metallurgica Sinica(English Letters) 1998年第3期11卷 215-224页

作者： Z.G.Li H.B.Chang t.y.hsu Z.y.Xu X.y.Ruan Shanghai Jiaotong Univ Shanghai China

Supposing carbon contents of ferrite phases in pearlite precipitating from austenite in multicomponent steel at temperature t and in Fe-C ystem at t' are the same the pearlite formation temperature diference, can be calculated from the FeX phase diagrams and the equilibrium temperature Al. Using tp and Fe-C binary thermodynamic model, the driving forces for phase transformation from austenite to pearlite in multicomponent steels have been successfully calculated. through the combination of simplified Zener and Hillert's model for pearlite growth with Johnson-Mehl equation, using data from known ttt diagrams, the interfacial energy parameter and activation energy for pearlite formation can be determined and expressed as functions of chemical composition in steels by regression analysis. the calculated starting curves of pearlitic transformation in some commercial steels agree well with the experimental data.

关键词： pearlite formation temperature difference interfacial energy parameter activation enerpy for pearlite transformation,Johnson-Mehl equation

tHEOREtICAL PREDICtION OF PROEUtECtOID FERRItICtRANSFORMAtION IN HyPO-PROEUtECtOID StRUCtRAL StEELS

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Acta Metallurgica Sinica(English Letters) 1998年第3期11卷 207-214页

作者： H.B.Chang Z.G.Li t.y.hsu Z.y.Xu X.y.Ruan Shanghai technical Coll of Metallurgy Shanghai China

Proeutectoid ferrite with carbon content xo precipitating from austenite in a multicomponent steel at temperature t is supposed to be equivalent to proeutectoid ferrite with the same carbon content precipitating from austenite in Fe-C binary system at temperature t'.is described as the temperature difference of proeutectiod ferrite formation, and can be calculated from the Fe-X diagrams and the equilibrium temperature A3. By introducing tf and basing on the thermodynamic model for Fe-C binary alloy, the driving force for phase transformation from austenite to proeutectoid ferrite in multicomponent steels has been successfully calculated. through the Johnson-Mehl equation and using the data hem known ttt diagrams, the relationship between the chemical composition and the intedecial edenly packeter as well as activation energy for proeutectoid ferrite formation can be calculated. the starting curves of proeutectoid ferritic transformation calculated in this way in some hypo-proeutectoid structural steels agree well with the erperimental data.

关键词： proeutectoid ferrite formation temperature difference interfacial enerpy parameters activation energy for diffusion Johnson-Mehl equation

tHERMODyNAMIC CRItERION OF SPINODAL DECOMPOSItION IN tERNARy SyStEMS

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Acta Metallurgica Sinica(English Letters) 1991年第8期4卷 75-81页

作者： JIANG Bohong ZHANG Meihua WEI Qing XU Zuyao(t.y.hsu) Shanghai Jiaotong University,Shanghai,China Shanghai Jiaotong Univ Shanghai China

By expanding the Gibbs free energy of a ternary system into a taylor series with respect to the composition,a thermodynamic criterion of spinodal decomposition is conducted as G_(xx)(δx)2+2G_(xx)δxδy+G_(yy)(δy)~2tions of spinodal decomposition are *** G_(xx)y)~2-G_(xx)G_(yy)t is called unstable decomposition unrestricted by the direction of composition fluctuation;when G_(xx)y)~2-G_(xx)G_(yy)>0,or G_(xx)>0, G_(xy)~2-G_(xx)G_(yy)>0,as well as G_(xx)=0,are all considered as unstable decomposition restricted by the direction of composition fluctuation δx and δ*** phenomenon of turning round in composition during spinodal decomposition is attempted to be explained from above point of *** computer calculated ranges of unstable decomposition according to the criterion of spinodal decomposition on Cu-Ni-Fe ternary system is consistent with the experimental re- sults obtained from literatures.

关键词： spinodal decomposition thermodyamic criterion Cu-Ni-Fe

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材料的相变研究及其应用

上海交通大学学报 2001年第3期35卷 323-330页

作者：徐祖耀上海交通大学材料科学与工程学院上海200030

Fe- C和 Fe- X- C合金马氏体相变热力学的研究成果使结构钢的 MS温度能以热力学预测 .建立了铜基合金及 Fe- Mn- Si基合金马氏体相变热力学 ,为铜基和铁基形状记忆合金的成分和工艺设计提供基础 .提出了含 Zr O2 陶瓷 MS温度的热力学计... 详细信息

Fe- C和 Fe- X- C合金马氏体相变热力学的研究成果使结构钢的 MS温度能以热力学预测 .建立了铜基合金及 Fe- Mn- Si基合金马氏体相变热力学 ,为铜基和铁基形状记忆合金的成分和工艺设计提供基础 .提出了含 Zr O2 陶瓷 MS温度的热力学计算方法 ,以及其母相晶粒大小影响 MS的正确表达式 ,对陶瓷的生产和工业应用都具有意义 .修正马氏体变温相变动力学方程 ,显示低碳钢中影响碳扩散系数的合金元素影响残余奥氏体量 ,这有利于低碳马氏体组织钢的开发 .GCr1 5轴承钢中残余奥氏体→马氏体的等温动力学研究显示 :钢经淬火后 ,再进行等温处理以形成很少量的等温马氏体 ,再作回火 ,提高钢件的尺寸稳定性 (经 1 0 0 0 d后与淬火 -回火比较 ,在接触疲劳寿命并不降低的条件下 )达 34% .研究了 Ni- ti、Cu- Zn- Al、Fe- Mn- Si基合金及 Zr O2 陶瓷的马氏体相变及其逆相变特征 ,揭示了影响这些材料形状记忆效应 (SME)的一些因素 ,并指出了改善 SME的途径 ,有利于这些材料的开发应用 .贝氏体相变的热力学研究 ,观察到生长台阶 ,母相强化对相变影响的研究以及内耗测量结果 ,均显示贝氏体相变属扩散型机制 .Cu- Zn- Al中加入阻碍 Zn和 Al扩散的合金元素可能提高形状记忆使用寿命 .揭示 Ce O2 - Zr O2 中存在贝氏体相变 ,?

关键词：材料工程金属材料陶瓷马氏体相变贝氏体相变相变热力学形状记忆效应

tHERMODyNAMICS OF MARtENSItIC tRANSFORMAtION IN Fe-Mn-C AND Fe-Ni-C ALLOyS

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Acta Metallurgica Sinica(English Letters) 1990年第1期3卷 16-21页

作者： XU Zuyao(t.y.hsu) PAN Mu Shanghai Jiaotong University,Shanghai,China Correspondent:XU Zuyao(t.y.hsu) Professor,Department of Materials Science,Shanghai Jiaotong University,Shanghai,China

A Central Atom Model is introduced and the LFG and hsu models are modified in order to evaluate the driving force for the martensitic transformation in Fe-Mn-C and Fe-Ni-C al- *** results show that the relationship between the driving force and the yield strength of austenite at Ms temperature,σ_(0.2)~γ/M_s,fits hsu's formula;ΔG~=2.1σ_(0.2)~γ/M_s+907 J/*** M_s temperatures of Fe-Mn-C and Fe-Ni-C alloys are also *** calculated results are in good agreement with experimental values.

关键词： Fe-Mn-C alloy Fe-Ni-C alloy martensitic transformation