非晶合金Fe76.5—xCu1.0NbxSi13.5B9.0的穆斯堡尔研究

非晶合金Ｆｅ７６．５－ｘＣｕ１．０ＮｂｘＳｉ１３．５Ｂ９．０（ｘ－１，３，５和７）穆斯堡尔研究表明，Ｎｂ元素对非晶合金的磁有序温度Ｔｃ和超精细相互作用很大的影响，Ｎｂ元素使非晶体Ｆｅ－Ｆｅ间的平均磁相互作用减弱，是造成晶非合金不均匀的重要因素。     

FeBSi非晶合金常规和电脉冲加热退火脆化及其微结构的研究

对非晶Ｆｅ７８Ｂ１３Ｓｉ９合金进行了低温等时及电脉冲加热退火处理，用高分辨率电子显微系统观察分析了合金脆化前后的微观结构变化，试验结果表明，常规退火时合金的低温脆化是其淬态在类Ｆｅ３Ｂ原子排列程有区长大至３～７ｎｍ所致，电脉冲加热由于能抑制类Ｆｅ３Ｂ有序区的发展并使其“碎化”而避免脆化的发生，电脉冲加热合金的脆化与ｂｃｃ－ａ－Ｆｅ晶粒的形核有关。     

Fe73.5 Cu1 Nb3 Si13.5 B9非晶合金的激光晶化

用CO2连续激光在不同功率、相同的速度条件下辐照Fe73.5Cu1Nb3Si13.5B9非晶带，然后用穆斯堡尔谱详细研究材料的微观结构。研究发现当扫描速度和散文斑直径一定的情况下，适当选择激光功率，Fe73.5Cu1Nb3Si13.5B9可以实现微量晶化。     

FeBSi非晶合金常规和电脉冲加热退火脆化及其微观结构的研究

对非晶Ｆｅ７８Ｂ１３Ｓｉ９合金进行了低温等时及电脉冲加热退火处理。用高分辨率电子显微系统观察分析合金脆化前后的微观结构变化。试验结果表明，常规退火时合金的低温脆化是其淬态存在的类Ｆｅ３Ｂ原子排列短程有序区长大至３～７ｎｍ所致；电脉冲加热由于能抑制类Ｆｅ３Ｂ有序区的发展并使其“碎化”而避免脆化的发生。电脉冲加热后合金的脆化与ｂｃｃα－Ｆｅ晶粒的形核有关。     

CO2激光辐照工艺对非晶Fe73.5Cu1Nb3S13.5B9合金晶化的影响

在较低激光功率(40～170 W)和两种扫描速度(10mm/s,5mm/s)辐照条件下,研究了CO2激光辐照工艺对非晶Fe73.5Cu1Nb3S13.5B9合金晶化行为的影响.用穆斯堡尔谱(MS)技术对原始态和晶化后样品进行了结构分析.研究发现:非晶Fe73.5Cu1Nb3S13.5B9表面产生了少量晶化,晶化相为Fe-Si结构;晶化量在2.1%～3.57%内,随激光功率的增加而增加.当激光功率较低时,低扫描速度对晶化的促进作用大于激光功率的作用;但是,随激光功率增大,速度的影响变弱.表面微观硬度随激光功率的增加而增加.     

FeAl合金的高能球磨穆斯堡尔谱研究

采用真空电孤炉熔炼制备Fe50Al50合金，Fe50Al50合金的穆斯堡尔谱线为单峰，这说明完全有序B2-FeAl合金是无磁性的。将有序B2-FeAl合金进行球磨100、120h后，再测量该粉末的穆斯堡尔谱，得到的是展宽的多峰谱线。这表明，球磨后合金样品发生了有序-无序转变，可以通过无序化来提高FeAl合金的磁矩。     

Fe-V合金中57Fe的超精细参数

本文用穆斯堡尔效应研究了Fe_1·xV_x(0<x<0.843)合金中⁵⁷Fe的超精细参数-同质异能移位,电四极分裂和磁超精细场,并且讨论了合金中V原子对超精细参数的影响。     

表面纳米化诱导GCr15钢渗碳体溶解行为研究

高能机械球磨表面纳米化过程中发现表面纳米晶层内渗碳体发生溶解现象,采用TEM、三维原子探针和穆斯堡尔谱对渗碳体的溶解进行了表征。TEM观察结果表明,在纳米化的最表层平均晶粒为10 nm,在选区电子衍射花样中没有发现渗碳体的衍射环,表明渗碳体可能发生溶解。三维原子探针分析表明,表面纳米化处理后,铁素体中的碳含量为0.75at%,是基体铁素体碳含量的100倍,表明表面纳米化过程中渗碳体发生了溶解,通过穆斯堡尔谱分析结果表明,渗碳体的溶解量约为47%。表面纳米化过程中渗碳体的溶解可分为三个阶段：①诱导阶段,在表面机械研磨的最初5 min,渗碳体的溶解分数仅为0.4%;②溶解阶段,在表面纳米化处理的5-30 min,渗碳体大量溶解,其体积分数由14.6%降低到8.4%;③饱和阶段,当处理时间达到30 min以上,渗碳体的体积分数基本保持不变。     

水雾化制备Fe-Si-B-C非晶软磁粉末及其晶化过程的研究

采用水雾化方法制备了Fe-Si-B-C四元非晶合金粉末。研究了粉末的粒度分布、相结构、微观形貌、热稳定性以及基本软磁性能,并通过Kissinger峰移法计算了其晶化时所需的激活能。结果表明,通过水雾化方法制备的Fe-Si-B-C四元软磁粉末的粒度分布合理;粒径小于38μm的粉末为完全非晶结构,且粉末表面光滑,内部成分均匀;非晶粉末的初始结晶温度为542.15℃,且升温过程中存在2个晶化放热峰;2个晶化反应对应的晶化激活能分别为463.92 k J/mol和910.21 k J/mol;粉末的饱和磁感应强度和矫顽力分别为1.08 T和111.4 A/m。     

Effect of yttrium on thermal stability and crystallization behavior of Nd60Fe20Al10Ni10 amorphous alloys

The effect of yttrium on the thermal stability and crystallization behavior of Nd-Fe-Al-Ni amorphous alloys was investigated using X-ray diffraction （XRD）, differential scanning calorimeter （DSC）, and transmission electron microscopy （TEM）.The results indicated that the as-cast Nd60Fe20Al10Ni10-xYx（X=-0, 2） amorphous alloys were fabricated with some quenched-in crystals, which could be restrained by Y. With the effect of yttrium, both the crystallization temperature and exothermic peak shifted to higher temperatures, illustrating that the thermal stability could be improved. The addition of Y changed the crystallization process and final crystallization results. Moreover, the crystallites in the amorphous matrix became more homogeneous and smaller. Meanwhile, Y was useful for the passivation of oxygen in chemistry and restrained the negative effect of oxygen. The activation energies of the start of crystallization and peaking were 1.21 and 1.16 eV, respectively, according to the Kissinger equation.     

升温速率对钛渣赤泥粉煤灰微晶玻璃析晶的影响

以钛渣代替二氧化钛为晶核剂制备赤泥粉煤灰微晶玻璃,对其微观形貌进行表征,并考察钛渣添加量对微晶玻璃的析晶动力学参数和微观形貌的影响。结果表明,随着钛渣添加量的增多,析晶活化能呈逐渐减小的趋势,晶化指数呈逐渐增大趋势。当钛渣的添加量为6.6%时,活化能降低为581.45kJ/mol,晶化指数为0.8,出现了分布均匀的晶核,晶粒明显长大,析晶效果较好。     

Kinetic study on the non-isothermal crystallization of Gd53Al24Co20Zr3 bulk metallic glass

Gd-based bulk metallic glass has drawn strong attention because of its large magnetic entropy changes. Thermal stability of metallic glass is a very important issue for its application. In the paper, crystallization behavior of Gd53Al24Co20Zr3 bulk metallic glass was investigated using non-isothermal differential scanning calorimetric (DSC) technique. Attention was given to the analytic details. The crystallized volume fractions as a function of temperature were derived from the DSC signals, where heat capacity change between amorphous phase and crystalline phase was considered. The local activation energies at different crystallized volume fraction were estimated using Doyle-Ozawa and Agrawal methods. The results suggested that the Doyle-Ozawa equation was appropriate to get local activation energy due to its simplicity and accuracy. The local activation energy depended on the crystallized volume fraction. Function reflecting crystallization mechanism was also deduced. The crystallization mechanism of the Gd-based bulk metallic glass was discussed.     

Effect of glass network modifier R2O (R=Li,Na and K) on upconversion luminescence in Er3+/Yb3+ co-doped NaYF4 oxyfluoride glass-ceramics

The effect of glass network modifier R2O (R=Li, Na, K) on upconversion luminescence in Er3+/Yb3+ co-doped NaYF4 oxyfluoride glass-ceramics was investigated. NaYF4 nanocrystals with different sizes were...     

镁热还原法制备无定形硼粉绝热温度的计算与动力学研究

随B2O3过量系数γ的增加,Mg热还原B2O3反应3Mg(l) B2O3(l)=3MgO(s) 2B(s)的绝热温度(Tad)降低.当B2O3的过剩系数γ小于1.102时,反应才能以正常的自蔓延方式进行,此时该反应的绝热温度Tad等于1800K.由DTA曲线分析可知,该反应起始反应温度在750～810℃之间,属于液-液反应机制.通过计算可知:反应3Mg(l) B2O3(l)=3MgO(s) 2B(s)的表观活化能E=18.8kJ*mol-1,反应级数为n=0.7.