扫描电子显微镜的安装与验收

本文就如何安装调试与验收扫描电子显微镜作了简单介绍,并以日立S-570型号例,对验收技术指标、方法及误差计算进行了具体说明。     

U71Mn重轨断裂原因分析

采用扫描电镜等技术手段,对重轨的断口和裂纹特征进行了分析,结果指出,钢中的较大夹杂物(100μm左右)为裂纹源,对重轨断裂有直接影响。此外,碳含量和夹杂物总量偏高也是重轨断裂的主要原因。     

超微金赋存状态的研究

本文利用EPMA、SEM/EDX、及TEM/EDX等分析技术,对我国某些卡林型金矿中金的赋存状态进行了研究。这些分析方法的综合运用,明确揭示出所谓的“不可见金”是由几十埃到几千埃不同粒级构成的被包裹于黄铁矿、含砷黄铁矿、粘土及石英等载金矿物中的超微金粒,并在粘土中首次获得45(?)的自然金颗粒。此研究结果,为评价金的存在形式提供了科学依据。     

扫描电镜及能谱仪的主要功能开发

文章着重介绍了包钢新引进的LEO 5.0HV型扫描电子显微镜的基本功能,并介绍了针对目前包钢产品能够进行的常规检测分析.     

昆钢技术中心大型精密检测分析仪器（一）——X射线衍射仪

技术中心作为昆钢技术管理、技术创新的主体，在人才、装备等各方面都得到了公司的高度重视，取得了快速发展。目前已装备了钢铁生产，新产品、新材料开发研究较完备的试验检测分析设备。其中，包括X射线衍射仪、扫描电子显微镜、透射电子显微镜、热分析仪等当代先进的大型精密分析仪器，为了更好地让广大科技工作者、工程技术人员了解这些大型精密分析仪器，使其在生产科研中发挥更大的作用。[第一段]     

粉末试样的扫描电镜观察方法

阐述了用扫描电镜研究粉末试样的分散技术、固定方法和镀膜技术。对于各种不同粒度的粉末试样，推荐了不同的既简便又可靠的制备方法。研究了用扫描电镜观察粉末试样时加速电压和束流的选择。通过研究和试验获得了实用的试验技术和理想的观察结果。     

Stable icosahedral phase in Mg_（44）Zn_（44）Gd_（12） alloy

The microstructure of the as-cast Mg 44 Zn 44 Gd 12 alloy was investigated by using X-ray diffraction(XRD),differentical scanning(DSC),scanning electron microscopy(SEM) and a detailed transmission electron microscope.The XRD,DSC and SEM results indicated that the as-cast Mg 44 Zn 44 Gd 12 alloy were mainly composed of three types of phases:the primary solidification phase,the dendritic phase and the eutectic phase.The primary solidification phase had an icosahedral structure.The dendritic phase was the W-phase,and eutectic structure phase was the Mg 7 Zn 3 phase.Microstructures of icosahedral phase(I-phase),W-phase and Mg 7 Zn 3 phase in Mg 44 Zn 44 Gd 12 alloy were investigated.The results indicated that the I-phase in Mg 44 Zn 44 Gd 12 alloy was a face-centered icosahedral quasicrystal with stoichiometric composition of Mg 42 Zn 50 Gd 8 which had an excellent thermal stability up to 420 °C.The solid solution of the Gd gradually decreased during solidification,which played an important role in activating the formation of Mg 7 Zn 3 phase and W-phase from icosahedral phases.     

Evolution of microstructure and tensile properties of extruded Mg-4Zn-1Y alloy

In order to investigate the effect of extrusion on Mg-4Zn-1Y alloy, microstructure and mechanical properties were analyzed by optical microscopy（OM）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, X-ray diffraction（XRD）, energy dispersive spectrum（EDS） and tensile testing.The results indicated that the microstructure was obviously refined by extrusion and dynamic recrystallization.The second phases were dynamic precipitated and distributed more dispersively through extrusion.W-Phases（Mg3Zn3Y2） were twisted and broken, while I-Phases（Mg3Zn6Y） were spheroidized by deformation.Twin bands were formed to achieve the large deformation and hinder the slip of dislocations effectively to improve tensile properties.The tensile strength and elongation of extruded Mg-4Zn-1Y alloy were 254.94 MPa and 17.9% respectively which were improved greatly compared with those of as-cast alloy.The strengthening mechanisms of the extruded alloy were mainly fine-grain strengthening and distortion strengthening.     

Microstructure and electrochemical properties of melt-spun Nd_(0.8)Mg_(0.2)(Ni_(0.8)Co_(0.2))_(3.8) hydrogen storage alloy

The effects of rapid solidification on the microstructure and electrochemical properties of Nd0.8Mg0.2(Ni0.8Co0.2)3.8 alloy were systematically investigated.The microstructure of alloys was characterized by scanning electron microscopy(SEM),X-ray diffractometer(XRD) and transmission electron microscopy(TEM).It was found that the melt-spun Nd0.8Mg0.2(Ni0.8Co0.2)3.8 ribbons became thinner and the average grain size of the ribbons became smaller with increasing wheel speed.A fraction of amorphous phase was observed for the ribbons melt-spun at high wheel speed(≥20 m/s).Microstructural characterization revealed that two phases:(Nd,Mg)2(Ni,Co)7 main phase(Ce2Ni7 type structure) and NdNi5 second phase(CaCu5 type structure),existed in the samples in cast state and melt-spun.The cycle stability of the melt-spun alloys was significantly enhanced as compared with cast alloy,and the sample prepared at wheel speed of 20 m/s exhibited good comprehensive electrochemical properties.     

Effect of aging on microstructure of Mg-Zn-Er alloys

The effect of aging on microstructure of Mg-Zn-Er alloys at 473 K was investigated using hardness measurement,scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results indicated that both Mg3.8Zn1.5Er and Mg5Zn2.0Er alloys exhibited visible age-hardening effect,especially the latter alloy.Microstructure analysis showed that,after being aged,lots of fine MgZn2 phases with hexagonal structure were found in the α-Mg matrix.Comparing with Mg3.8Zn1.5Er alloy,the accelerated hardenin...     

Effects of Nd on microstructure and mechanical properties of as-cast Mg-8Li-3Al alloy

Effects of Nd on microstructure and mechanical properties of as-cast Mg-8Li-3Al alloy were investigated by OM,X-ray diffraction(XRD),EPMA,scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS).The results showed that the dendrites sizes of α phase were decreased by the Nd addition.When the amount of addition Nd was 1.6 wt.%,the alloy with the smallest α phase was obtained.The refining mechanism mainly owed to the increasing constitutional supercooling at the solidification front.Furthermore,the compound Al 2 Nd generated by the reaction of Al and Nd,which distributed at the phase boundary and inside β phase,could also restrain the growth of α phase.Nd could improve the tensile strength and elongation of Mg-8Li-3Al alloy,however,excessive Al 2 Nd might also become crack source and decrease the elongation.     

Mg-10Gd-4.8Y-0.6Zr合金在520℃下的固溶处理行为

采用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、显微硬度测试、热分析、能谱分析以及X射线衍射(XRD)等手段,研究Mg-10Gd-4.8Y-0.6Zr合金铸态和520℃固溶处理不同时间后的显微组织以及显微硬度分布.结果表明:Mg-10Gd-4.8Y-0.6Zr合金经520℃/16 h固溶处理后,铸态时的...     

Mg-xZn-1Mn镁合金均匀化热处理及扩散动力学研究

采用光学显微镜、扫描电镜、能谱分析、X射线衍射、布氏硬度测试等材料方法,研究了新型变形镁合金Mg-xZn-1Mn(x=4%,5%,6%,质量分数)的铸态合金以及均匀化热处理T4和时效处理T6后合金的显微组织、成分以及硬度的演变规律,建立ZM合金的热处理制度。并以空位扩散机制为基础,研究均匀化扩散动力学过程,建立ZM合金的均匀化扩散方程。结果表明:在ZM系列合金中,铸态组织枝晶偏析严重,晶界上有许多粗大的Mg-Zn共晶组织,Mn主要以单质形式存在于合金中。随着Zn含量的增加,合金的化合物体积分数增加,枝晶明显细化。得出3种合金合理的均匀化处理工艺分别是:ZM41为370℃×12 h;ZM51为390℃×12 h;ZM61为390℃×20 h。随着Zn含量的增加,热处理的温度和时间增加。在均匀化过程中,随均匀化处理温度提高,均匀化程度越高,时效硬化效果越好。经均匀化热处理后,大部分的Mg7Zn3相溶入基体。通过扩散动力学计算得到ZM41合金的均匀化处理温度与时间的关系为0.0008/t=exp(- 1160T9.5/T),570 K相似文献   

EW75镁合金高温扩散动力学研究

采用光学显微镜(OM)、扫描电子显微镜(SEM)和能谱分析(XRD),观察EW75合金大型铸锭原始态及高温热处理之后的组织及成分分布,以进行稀土元素在EW75合金中高温扩散动力学的研究。结果表明:EW75铸态合金中存在较为严重的局部偏析,大量非平衡凝固共晶组织在晶界处富集,Gd,Y,Nd在合金中的分布很不均匀,铸态组织呈大块的骨骼状,由α-Mg基体、Mg24Y5、Mg5Gd和Mg41Nd5非平衡凝固相组成,铸态合金晶粒尺寸约为100μm;在505及520℃保温24 h之后依然有较多未溶相残留在晶界上,由于温度稍微偏低,共晶组织未能完全溶解并分散到基体中;经过535℃,20 h高温热处理之后,共晶组织基本分解完全,稀土元素较为均匀地分布在基体中,晶粒长大非常明显;采用(EDS)分析测得各合金元素在EW75中的浓度分布,发现合金元素在EW75中成一定的规律分布,通过动力学方程计算得出了Y,Gd,Nd元素在不同温度下的lnδ-t关系曲线并进行线性拟合,最终得出Gd,Y,Nd在不同温度下的扩散系数。     

F-type icosahedral phase and a related cubic phase in the Al-Rh-Cu system

An F-type icosahedral phase and a related cubic phase (composition of Al_66.1Rh_21.5Cu_12.3, lattice constant a=1.5380(2) nm, and space group of Fm3) were observed in the Al₆₃Rh_18.5Cu_18.5 alloy by transmission electron microscopy (TEM). The structure of the Al-Rh-Cu cubic phase was determined by single-crystal X-ray analysis. A high-resolution electron microscopic image of the Al-Rh-Cu cubic phase is presented together with a simulated image. The structure of the cubic phase can be described by two types of atom clusters, which have outer shells with icosahedral symmetry. It is suggested that the structure of the Al-Rh-Cu cubic phase is helpful for understanding the structure of the i-Al-Rh-Cu F-type icosahedral quasicrystal.     

钕对NiAl基共晶合金高温流变行为的影响

 研究了钕对NiAl 28Cr 55Mo 05Hf共晶合金显微组织及高温流变行为的影响。结果表明：NiAl 28Cr 55Mo 05Hf基体合金是由黑色的NiAl相和灰白色的Cr(Mo)相组成的共晶组织，在相界处聚集有白色的Ni2AlHf(Heusler)相，加入稀土钕可细化组织；NiAl 28Cr 55Mo 05Hf(wNd=005%)合金在较高的应变速率(=194×10-2 s-1和=194×10-3 s-1)下，含稀土合金的流变应力大于不含稀土合金的流变应力，而在低应变速率(=194×10-4 s-1)下，这种强化现象消失。幂指数规律和温度补偿的幂指数规律可以很好地描述各种合金的高温压缩流变行为。加入稀土可降低合金的应力指数和变形激活能，这是因为稀土偏聚在相界上，致使相界上的空位浓度发生变化。