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Microstructure and Mechanical Property of Ni Metal treated by Surface Mechanical Attrition

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材料热处理学报 2004年第5期25卷 161-164页

作者： t.y. hsu School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200030China

A nanostructured surface layer can be formed in Ni metal treated by surface mechanical attrition (SMA). the microstructure was investigated by using optical microscope, X-ray diffractometer and transmission electron microscope, respectively. Mechanical property measurements indicate that the yield strength of the surface layer raises significant.y.while the tensile strength somewhat changes and the elongation percentage reduces severely compared with that of the inside layer. Meanwhile, yield-drop-like phenomenon occurs in the surface layer after SMA treatment. In order to compare the mechanical behavior of nanostructured materials with two phases, Fe-30Ni nanostructured alloy was also investigated.

关键词：显微结构表面层机械性能表面损耗镍合金

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条状马氏体形态对钢力学性质的影响

热处理 2009年第3期24卷 1-6页

作者：徐祖耀上海交通大学材料科学与工程学院上海200030

总结了有关条状马氏体形态对钢力学性质(主要为强度)影响的文献。由于马氏体束比领域小很多,且也具有高角度位向差界面,一般束宽为决定条状马氏体强韧性的主要因素。但当马氏体条宽在几十nm级时,条宽将对钢的强度和韧性作更大贡献。

关键词：马氏体形态条状马氏体领域束条宽力学性质

Fe-Ni-C合金中奥氏体固溶强化对马氏体相变的影响

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金属学报 1986年第6期 46-51页

作者：徐祖耀李箭曾振鹏上海交通大学

测定了5种不同成分Fe-Ni-C合金的Ms温度和奥氏体在Ms时的屈服强度σ0.2（Ms）。求得奥氏体在Ms温度时的固溶强化方程为:σ0.2（Ms）=25.9+3410XC+567XNi,MPa。Ni,C浓度对Ms温度的影响可以方程Ms（K）=829-8650XC-1766XNi表示,以及σ0.2... 详细信息

测定了5种不同成分Fe-Ni-C合金的Ms温度和奥氏体在Ms时的屈服强度σ0.2（Ms）。求得奥氏体在Ms温度时的固溶强化方程为:σ0.2（Ms）=25.9+3410XC+567XNi,MPa。Ni,C浓度对Ms温度的影响可以方程Ms（K）=829-8650XC-1766XNi表示,以及σ0.2（Ms）与Ms的线性关系为:σ0.2（Ms）≈210-0.323Ms（℃）,MPa.说明奥氏体在Ms时的固溶强化形成马氏体相变的阻力,它和相变驱动力及与Ms均呈线性关系.含25wt-％Ni,含碳在0.11Wt-％的合金基本形成位错马氏体,仅有极少量孪晶,当含碳为0.12wt-％时,则以23.97wt-％Ni为位错和孪晶亚结构的临界含Ni量.利用Magee和Davies图导出了奥氏体的σ0.2（Ms）对Fe-Ni-C合金马氏体形态的影响图,推断出奥氏体的临界分切应力随σ0.2（Ms）的变化关系,借以解释位错型和孪晶型马氏体的形成。

关键词：奥氏体 γ固溶体金相相组成固溶强化零维强化强化(金属学) 马氏体相变马登斯相变位移性相变 Ni

Cu-26Zn-4Al形状记忆合金马氏体相变晶体学 Ⅱ.群论的应用

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金属学报 1986年第3期 56-62页

作者：朱伟光陈伟业徐祖耀上海交通大学

本文试图用群论的理论分析,探讨Cu-Zn-Al合金马氏体相变的晶体学性质:由群的表示理论找得诱导该合金B结构母相β→非规则9R马氏体的不可约表示;由群论讨论该合金马氏体相变具有24个变态的可能性,找出由组态组成的自协调组织的对称性群Dh... 详细信息

本文试图用群论的理论分析,探讨Cu-Zn-Al合金马氏体相变的晶体学性质:由群的表示理论找得诱导该合金B结构母相β→非规则9R马氏体的不可约表示;由群论讨论该合金马氏体相变具有24个变态的可能性,找出由组态组成的自协调组织的对称性群Dh,揭示了变态间的对称联系和分布规律。

关键词：形状记忆合金 Cu-26Zn-4Al 母相记忆合金精密合金马氏体相变晶体学不可约表示群表示 Zn 群论数学理论 Al

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贝氏体相变简介

热处理 2006年第2期21卷 1-20页

作者：徐祖耀上海交通大学材料科学与工程学院上海200030

钢、有色合金和一些陶瓷材料中都存在贝氏体相变。贝氏体钢正成为有益的工程材料。总结评述切变学派和扩散学派作者们以形貌、动力学或晶体学对贝氏体相变机制所持的论点。钢中贝氏体相变以过饱和铁素体开始形成之说迄未得到支持。一些... 详细信息

钢、有色合金和一些陶瓷材料中都存在贝氏体相变。贝氏体钢正成为有益的工程材料。总结评述切变学派和扩散学派作者们以形貌、动力学或晶体学对贝氏体相变机制所持的论点。钢中贝氏体相变以过饱和铁素体开始形成之说迄未得到支持。一些实验已发现替代(置换)型合金元素在相界面上的偏聚,并以此所呈现的拖曳效应说明相变的不完全现象,切变学者以切变机制来解释这个现象,但此现象不是钢中贝氏体相变的普遍情况。贝氏体形成时呈现帐篷形浮突,不具不变平面应变特征;有时马氏体相变晶体学表象理论能近似地应用于贝氏体相变晶体学,但不能以此来判定其相变机制为扩散或切变。溶质拖曳效应以及高分辨电镜对相界面结构实验、热力学研究、磁场和应力场对贝氏体相变影响以及一些预相变现象都确证贝氏体相变籍扩散机制进行。本文作者定义贝氏体为:在Ms温度以上,经扩散相变的产物,多呈片状,形成时会在自由表面上呈现帐篷形浮突。提出贝氏体相变机制进一步研究和应用的展望。

关键词：贝氏体相变相变机制扩散相变切变相变动力学晶体学热力学贝氏体钢

A Mixed-control Mechanism Model of Proeutectoid Ferrite Growth under Non-equilibrium Interface Condition in Fe-C Alloys

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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) School of Materials Science and Engineering Shanghai Jiao Tong University 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

Interaction between antiferromagnetic transition and martensitic transformation in Fe-Mn-Si based shape memory alloys

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Progress in Natural Science:Materials International 1999年第6期 55-63页

作者：吴晓春 hsu t.y. 徐祖耀 China China Laboratory of Solid State Microstructures Department of Materials Science Nanjing 210008 Nanjing University Shanghai 200030 Shanghai Jiao tong University

Internal friction and elastic modulus of Fe-Mn-Si, Fe-Mn-Si-RE and Fe-Mn-Si-Cr shape memory alloys were measured from 150 K to 600 K by using an electrostatic audio-frequency internal friction instrument. the mtei-nal friction characteristies of the antiferromagnetic transition and γ-ε martensitic transformation as well as the interaction between these two transitions have been investigated. the results show that the γ→ε martensitic transformation is part.y.restrained, but can still continue below the Neel temperature ( tNγ) . When the temperature tN is slight.y.below the MS temperature, the internal friction peak associated with the paramagnetic → antiferromagnetic transition disappears upon cooling due to the occurrence of the γ→ε martensitic transformation, and only the internal friction peak associated with the γ→ε martensitic transformation can be observed. When the Neel temperature ( tNγ) is much below the temperature MS, the internal friction peaks appear near tNγ and MS respective

关键词： Fe-Mn-Si based shape memory alloys antiferromagnetic transition martensitic transformation internal friction.

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