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用透射电子显微镜对不同轧制变形量的Ti-28 Nb-15Ta-4Zr合金进行观察分析.结果表明,该合金在轧制前为单相体心立方β相合金,在轧制变形过程中有形变诱发马氏体α"相形成,α"相为正交晶系,单胞参数a=0.3152 nm,b=0.4854 nm,c=0.4642 nm.β相与α"相的位向关系为[100]α"//[(-100)]β,[010]α"//[01(-1)]β,[001]α"//[0(-1)(-1)]β,(100)α"//((-1)00)β,(010)α"//(01(-1))β,(001)α"//(0 (-1)(-1))β.据此提出形变诱发马氏体α"相变是以(0 (-1)(-1))β为不变平面转变为(001)α",在((-1)00)β和(01(-1))β面上原子经过微小迁移转变成(010)α"和(100)α"的马氏体相变机制. 相似文献
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钛合金相变的电子显微镜研究(Ⅲ):钛合金中的马氏体相变 总被引:7,自引:1,他引:7
张廷杰 《稀有金属材料与工程》1989,(4):71-78
本文重点介绍了工业钛合金中马氏体相变的结晶几何学,两类马氏体α′和α″相的电子衍衬象和电子衍射特征,和两类马氏体的时效分解过程及时效产物的形态。 相似文献
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对β-ZrTiAlV合金分别采用室温和液氮低温轧制变形,通过X射线衍射(XRD)、光学显微镜(OM)、背散射电子衍射(EBSD)分析技术,研究轧制温度和轧制变形量对β-ZrTiAlV合金形变诱导马氏体相变及其微观组织演变规律的影响。实验分析结果表明,在室温或低温条件下变形后合金组织中都发生了β→α'形变诱导马氏体相变,同时在马氏体α'中产生(102)<110>孪晶,轧制变形量的增加促进相变马氏体的形成和孪晶变体数量的增加,而低温变形则抑制了形变诱导马氏体的形成,但更有利于孪晶的产生。轧制变形量为5%时,形变诱导马氏体以板条状分布于原始β晶粒中,当变形量增至10%后,少数β晶粒完全转变为α'相。 相似文献
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MnCu合金马氏体相变和马氏体的内耗 总被引:2,自引:0,他引:2
本文对含Mn60-90wt-%的MnCu合金在123—423K温度范围内进行了低频和声频内耗测量,研究马氏体相变和马氏体中各种界面对内耗的贡献.结果指出,马氏体相变内耗可分解为两部分,即相变中的稳定内耗峰(阶梯变温测量时,T=0)和低温背景内耗.相变内耗主要是由马氏体和母相界面的运动产生的;低温背景内耗是由马氏体片间界面的运动产生的,且表现出强烈的振幅效应,其强弱决定于马氏体片间界面的数量.马氏体片间界面的运动产生的非线弹应变导致了附加的模量亏损和非线性共振行为.高Mn合金(Mn>80wt-%)中的弛豫型内耗峰研究指出,该峰的弛豫时间分布参数服从β=|β_0-β_Q/k_B T|. 相似文献
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朱祖昌 《热处理技术与装备》2012,33(3):65-68
4马氏体相变动力学4.1定性动力学[3]从定性角度分析,马氏体相变动力学分以下两类:(1)马氏体转变具有动态稳定化特性,以Fe-C合金为典型,合金钢也属于这一类。马氏体转变分数f取决于冷却达到的温度Tq,即与(Ms-Tq)有关, 相似文献
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采用剥落腐蚀实验、电化学阻抗测试、透射显微技术等方法,研究了不同冷轧变形量对Al-Zn-Mg-Cu合金组织和剥落腐蚀性能的影响.结果表明:随着冷轧变形量的增加,合金在EXCO溶液中剥落腐蚀增大.变形量主要通过改变晶粒形态及晶界析出相影响合金的剥落腐蚀性能.一方面冷变形导致合金晶粒纵横比增大,使得腐蚀裂纹尖端处产生的楔入应力增加,裂纹扩展速率提高;另一方面,较大冷变形合金时效时形成的连续晶界析出相易成为阳极腐蚀通道,也会加速剥落腐蚀进程. 相似文献
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NiPt合金溅射靶材是半导体工业制备NiPtSi接触层的重要原材料。本文对NiPt5合金在冷轧过程中的结构演变及磁性能进行研究。结果表明:NiPt5合金在冷轧过程中微观结构的演变经历位错缠结、位错壁、含小角晶界的拉长亚晶粒、新晶界形成4个阶段。晶粒细化主要是位错的聚集、湮灭和重排所导致。NiPt5的矫顽力随着轧制变形量的增加而增加,这归因于冷轧诱导的缺陷及内应力对畴壁移动的阻碍。剩磁与NiPt5合金择优取向密切相关,(200)织构导致剩磁升高。Ni合金较高的磁各向异性使á200?取向的织构对提高靶材质量十分有利。 相似文献
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通过分析固溶态Cu-Ni-Si合金时效过程中导电率的变化,根据导电率与新相析出量之间的关系计算时效过程中新相的转变比率,在此基础上,确定不同温度下描述时效析出相转变比率与时效时间的Avrami相变动力学经验方程和导电率随时间变化的导电率方程,绘制出动力学"S"曲线,并且用固态热分解反应机理的积分方程验证用Avrami经验方程来描述合金的析出过程的正确性。对Cu-Ni-Si合金在500℃时效8 h后的析出相进行选区电子衍射花样标定,发现析出相为δ-Ni2Si和β-Ni3Si。 相似文献
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《Intermetallics》2015
Hexagonal martensite with well-developed midribs was obtained by iced-brine quenching of Ti44Al4Nb4Hf0.1Si from the beta phase field. Crystallographic characterisation shows great resemblances of the martensite in this alloy to the lenticular martensite in Fe–Ni alloys in the morphology and substructures of martensite plates. It also bears similarities with the martensite in titanium and its alloys in habit planes and orientation relationship with parent phase. Martensitic transformation under the conditions employed in this work was incomplete and the remaining beta phase after martensitic transformation, thus, underwent diffusional beta-to-alpha transformation or massive transformation, depending on the local circumstances. 相似文献
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Minh Son Pham Kyoung-Won Park Byung-Gil Yoo Jae-Il Jang Jae-Chul Lee 《Metals and Materials International》2009,15(2):209-214
This study reports the plasticity improvement of amorphous alloy associated with skim cold rolling. It was found that, with
an increasing reduction in thickness of up to 6 %, the plastic strain increased considerably from 1.5 % to 9.6% while the
yield strength deceased slightly from 1.75 GPa to 1.68 GPa. With further rolling beyond 6 %, the changes in the plasticity
and yield strength were observed to be insignificant. In this study, we discussed the principle underlying the improved plasticity
of amorphous alloy in view of the creation of excess free volume during skim cold rolling. 相似文献
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Effect of particles on microstructural evolution during cold rolling of the aluminum alloy AA3104 总被引:1,自引:0,他引:1
The effect of second-phase particles on the evolution of the deformation microstructure during cold rolling of the particle-containing aluminum alloy AA3104 has been investigated using electron channeling contrast imaging and electron backscattered diffraction (EBSD). The results show that the influence of second-phase particles on the deformation microstructure depends on the particle size. Fine dispersoids present in the microstructure have no clear effect on the grain orientation dependence of the dislocation structures formed in the strain range examined. However, large scale structural heterogeneities, in the form of deformation zones, are formed near coarse constituent particles, leading to significant local distortions of the deformed microstructure. Analysis of EBSD data shows that significant orientation gradients are found in the vicinity of the coarse particles. Within the deformation zones the largest lattice rotations occur at the tips of plate-shaped constituent particles. A symmetrical pattern of TD-rotations of alternating sign is found in the deformation zones, with the magnitude of the lattice rotations increasing with increasing strain. 相似文献
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Ryoichi Chiba Tamon Nakamura Mitsutoshi Kuroda 《Journal of Materials Processing Technology》2011,211(11):1878-1887
In this study, the possibility of solid-state recycling of aluminium alloy machining swarf using cold extrusion and a subsequent cold rolling process is investigated. Cast Al-Si alloy swarf was cold compacted into billets and successfully profile-extruded into square bars with a rectangular cross-sectional aspect ratio of 1:1.8 under an extrusion ratio of 4 or more. After annealing, the extruded bars underwent multi-pass cold rolling into 1-mm thick strips with a total rolling reduction of 85%. Optical microscopy demonstrated that in material recycled using only an extrusion process, coarse residual voids existed in regions where insufficient plastic strain was introduced, causing a visible expansion of the material during heat treatment. However, uniaxial tensile tests showed that extrusion-recycled material had a higher mechanical strength than the original aluminium alloy, implying sufficient bonding among the individual pieces of machining swarf. It was also found that the strength and density of material recycled through extrusion and an additional rolling process were superior to material recycled using extrusion only. Moreover, it was observed that the ductility of the recycled materials was inferior to that of the original aluminium alloy. 相似文献