Fe61Co10Zr5W4B20块体非晶合金的形成及其力学性能

采用铜模吸铸法获得直径为2 mm的Fe61Co10Zr5W4B20块体非晶合金.采用X射线衍射、扫描电镜、示差扫描量热仪、微显硬度及压缩实验等研究了非晶合金的结构、热稳定性、显微硬度与压缩性能.结果表明:Mo的引入不利于非晶合金的形成;Fe61Co10Zr5W4B20块体非晶合金表现为二级晶化,玻璃转变温度为561.1℃,晶化起始温度为619.0℃,第一晶化峰值温度为632.6℃,第二晶化峰值温度为747.0℃,过冷液相区为57.9℃;该非晶合金的显微硬度为1207HV0.2,抗压强度σbc为1707.6 MPa.     

CuZr基块体非晶合金室温拉伸力学性能研究

由于受到制备尺寸和材料特性的限制,目前块体非晶合金力学性能的研究多集中在压缩力学性能的相关研究。选取Zr_(47)Cu_(46)Al_6Co_1块体非晶合金,研究该合金在室温条件下拉伸力学性能。实验结果表明,样品的拉伸断裂强度约为2 000 MPa,其断裂方式为无征兆的脆性断裂,断口表面光滑平整。其断口主要形貌为放射状的河流花纹,该图案是非晶合金拉伸断裂的典型形貌。根据样品的断口形貌观察,可以推断Zr_(47)Cu_(46)Al_6Co_1块体非晶合金室温拉伸断裂的方式与传统非晶合金拉伸断裂方式相一致。     

Fe60Co8Zr10Mo5W2B15块体非晶合金的形成及热处理对性能的影响研究

用铜模吸铸法获得直径为2mm的Fe60Co8Zr10Mo5W2B15和Fe60Co8Zr10Mo5W2B15块体非晶合金。采用X射线衍射（XRD）、示差扫描量热分析（DSC）、显微硬度及压缩实验等研究了非晶合金的结构、热稳定性及热处理前后的显微硬度与压缩性能。结果表明Nb的引入不利于非晶合金的形成；Fe60Co8Zr10Mo5W2B15非晶合金的显微硬度为1343HV0．2，抗压强度σbe为972．6MPa；在低于晶化起始温度的热处理，硬度稍有下降；但在高于晶化峰值温度的热处理，硬度值随时间变化先升高，后下降；在热处理时间相同的条件下，随着热处理温度的升高，合金的硬度升高，但压缩强度会明显下降。     

铜模吸铸法制备的Fe74Al4Sn2P10Si4B4C2块体非晶与块体纳米晶合金

利用铜模吸铸法制备了直径φ1.0mm和2.0mm的Fe74Al4Sn2P10Si4B4C2块体非晶合金和直径2.0mm的Fe74Al4Sn2P10Si4B4C2块体纳米晶合金圆棒.利用X射线衍射、差示扫描量热仪(DSC)和差热分析仪(DTA)对Fe74Al4Sn2P10Si4B4C2块体非晶合金的结构和热性质进行了测定.该非晶合金的超冷液相区△Tx为16.7K,约化玻璃转变温度Tg/Tm和Tg/T1分别为0.60和0.57.Fe74Al4Sn2P10Si4B4C2合金接近共晶成分,在10K/min的冷却速率下其过冷度可达86.7K.利用透射电子显微镜(TEM)观察了制备态的Fe74Al4Sn2P10Si4B4C2纳米晶合金圆棒的结构,为非晶基体上均匀分布的尺寸10～20nm的α-Fe晶粒.Fe74Al4Sn2P10Si4B4C2合金能达到较大的过冷度,具有较高的约化玻璃转变温度(接近共晶合金成分)和过冷合金熔体的二步相析出有利于块体非晶合金和块体纳米晶合金的形成.铜模吸铸法既可制备块体非晶合金,也可制备块体纳米晶合金,是一种很有吸引力的制备块体非晶合金和块体纳米晶合金的方法,并进一步证实利用快速凝固法可以直接制备块体纳米晶合金.     

Cu对Fe基非晶合金内禀磁性及晶化行为的影响

利用 DSC,XRD,TEM,M(?)ssbauer 谱及磁性测量技术研究了 Cu 取代 Fe 对 FeSiB 非晶合金的内禀磁性及晶化行为的影响。结果表明:Cu 元素取代 Fe 使 FeSiB 非晶合金的λ_s,σ_s,(?)_f,(?)_(Fe)下降,但居里温度 T_c 升高。而且,Cu 的加入能够显著地降低 FeSiB 非晶合金的晶化温度及晶化激活能,改善x-Fe(Si)相的形貌。FeCuSiB 非晶合金的晶化行为表明:在非晶合金内部存在α-Fe(Si)相成分富集区。     

Fe45Co7Cr15Mo10Y2B6C15大块非晶合金的晶化动力学研究

为了明确Fe基块体非晶材料的晶化过程,通过铜模吸铸法制备了Fe45Co7Cr15Mo10Y2B6C15块体非晶合金,采用连续和等温差热扫描量热法对非晶合金在1 000 K以下的晶化动力过程进行了研究.研究表明:在973 K时效后的晶化产物为铁的碳化物;晶化过程的激活能达到了555.9 kJ/mol,非晶热稳定性良好;Avrami常数n值接近2,随着退火温度的变化,n值没有明显的变化,非晶晶化机理没有发生改变,而放热峰宽随着退火温度的降低明显宽化,说明非晶晶化过程是一个二维扩散控制的形核与长大过程.     

不同微观结构Zr_(55)Al_(10)Ni_5Cu_(30)块体非晶合金的晶化过程

用差示扫描量热仪分别对具有相似晶体体积分数和晶化激活能的Zr55Al10Ni5Cu30块体非晶合金铸态、轧制态试样进行等温和连续升温实验,研究了不同微观结构块体非晶合金的晶化过程。结果表明,在晶化初期(小于30 min),两个试样具有相似的晶化速率;晶化后期(大于30 min),轧制态试样表现出较快的晶化速率。这在一定程度上表明,用JMA公式和晶化开始温度Tx及峰值温度Tp计算出的晶化激活能不能全面反映非晶合金的热稳定性。另外,剪切带中原子之间相互联接的减弱以及短程有序的强化,使轧制态试样热稳定性降低和晶化过程变快。     

预退火对Sm5 Fe74.3Nb1.5Si11.7 B4.5C2.5Cu0.5非晶合金晶化动力学的影响

研究了预退火对Sm5Fe74.3Nb1.5Si11.7B4.5C2.5Cu0.5非晶合金晶化动力学的影响。结果表明，预退火处理使非晶合金晶化相α-Fe和Sm2Fe17Cx的晶化温度（Tp）和晶化表观激活能（Ec）值降低，且改变晶化相α-Fe在晶化过程中晶化激活能的变化趋势，有助于该合金在晶化退火中形成晶粒尺寸较小的α-Fe相。     

块体非晶合金Gd_（36）La_（20）Al_（24）Co_（20）晶化行为的研究

为深入理解非晶合金的晶化行为,有效控制合金的微观结构和性能,本文利用铜模铸造法制备了Gd36La20Al24Co20块体非晶合金,通过X射线衍射和差示扫描量热法对该非晶合金的热稳定性和晶化行为进行了研究.结果表明：Gd36La20Al24Co20块体非晶合金的晶化激活能为282.5 kJ/mol;与轻稀土基非晶合金相比...     

Fe74Al4Ga2P12B4Si4块体非晶合金的纳米晶化及软磁性能研究

采用铜模铸造法制备了厚2mm的Fe74Al4Ga2P12B4Si4块体非晶合金.利用X射线衍射(XRD)、差热分析(DSC)和振动样品磁强计(VSM)研究了其晶化行为和软磁性能.结果表明,非晶合金的玻璃转变温度Tg为457.35℃,晶化开始温度Tx为497.65℃.合金的过冷液相区宽度△Tx达到40.30℃,表明合金具有较大的玻璃形成能力.F74Al4Ga2P12B4Si4合金的晶化是二级晶化过程.经520℃等温退火后析出α-Fe相,其晶粒尺寸为15.9nm;而经550℃等温退火后析出α-Fe相及微量的A10.3Si0.7Fe3和Fe3B相,其中α-Fe相的晶粒尺寸为17.4nm.非晶合金的饱和磁化强度为108.816emu/g、矫顽力Hc为574.97Oe;经520℃等温退火后,纳米晶合金的饱和磁化强度为106.875emu/g、矫顽力Hc为94.16Oe.退火实验结果表明,纳米晶化对材料的饱和磁化强度没有显著影响,但会显著降低材料的矫顽力.     

Observations of infrared bands of asymmetrical ozone isotopologues 16O16O18O and 16O18O18O

Infrared spectra (0.003 cm(-1) resolution) of 16O16O18O and 16O18O18O ozone isotopologues have been recorded and analyzed in the range 600-5000 cm(-1). Several thousand rovibrational lines belonging to 32 absorption bands have been measured and assigned. An accurate determination of band centers through the rovibrational analysis has been done, 12 bands being observed for the first time to our knowledge. In addition to atmospheric retrieval applications, these results are also useful for a validation of potential energy surfaces and for the study of isotope effects in dynamic processes of ozone.     

An integrated 16/spl times/16 PVDF pyroelectric sensor array

This paper presents a fully integrated PVDF-on-silicon pyroelectric sensor array. The pyroelectric sensor has two main features: a subpixel low noise charge amplifier and a self-absorbing layered structure. The integrated low noise charge amplifier is implemented in a standard CMOS process technology. It is located directly under the sensing structure, maximizing the pixel fill factor. The self-absorbing pyroelectric sensor is a three-layer stack, consisting of a conductive polymer as an absorber layer and front electrode, a thin PVDF film as the pyroelectric material, and a rear metal layer acting as a reflector layer and rear electrode. The manufacture of the pyroelectric sensor array requires five maskless post-CMOS processing steps and is compatible with any n-well, double metal, double polysilicon, CMOS process. The array has an average pixel voltage sensitivity of 2200 V/W at 100 Hz, an NEP of 2.4/spl times/10/sup -11/ W//spl radic/Hz at 100 Hz, and a specific detectivity of 4.4/spl times/10/sup 8/ cm /spl radic/Hz/W at 100 Hz.     

Polymerization of 16-heptadecenoic acid monolayers

Monolayers of heptadecenoic acid (vinyl acid) were spread at a gas-water interface. The terminal double bond of the vinyl acid enabled it to be polymerized on exposure to UV radiation. Pressure-area isotherms for both monomer and polymer vinyl acid were then recorded and compared with isotherms from similar compounds.Preliminary studies were conducted to minimize the degree of dissolution of the fatty acid. The polymerization kinetics were examined by the use of UV spectroscopy and measurements of the reduction in the area occupied by the film at a constant surface pressure. The reaction appeared to follow zero-order kinetics after an initial acceleration period. The rate constant for the reaction increased with increasing surface pressure.A dynamic mechanical test was performed to determine the mechanical properties of monolayers at the gas-water interface. Films were polymerized to various conversions and then examined to determine the relation between mechanical properties and conversion. A simple model is proposed to correlate the monolayer's structure and the dynamic mechanical data.