Haijian Ma
材料科学技术（英文）
The crystallization of the (Fe0.78Si0.09B0.13)100-xNix glassy alloys (x=0, 2 and 5) has been investigated by X-ray diffraction (XRD) and differential scanning calorimeter (DSC). Corrosion resistance analyses have been carried out using electrochemical measurements and corrosion products have been analyzed by scanning electron microscopy (SEM). The experimental results show that the addition of Ni can promote the nucleation of α-Fe, retard the decomposition of the metastable borides, and alter the crystallization mode of the present Fe-based glassy alloys. The lattice constant (aFe 0 ) of α-Fe in the annealed samples shows a decreasing trend with increasing annealing time. The Ni addition can improve the corrosion resistance of the as-quenched Fe-based glassy alloys in H2SO4, NaCl and NaOH solutions. The results indicate that Ni can promote the diffusion of Si atoms during quenching and annealing processes.processes.
关键词:
Crystallization
Chengdong LI
,
Xuelei TIAN
,
Xichen CHEN
,
A.G.Ilinsky
,
Likai SHI
材料科学技术（英文）
The crystallization kinetics of amorphous Fe¬¬68.5Si¬13.5B¬9Cu¬1Nb¬3C¬5 (at. pct) melt-spun ribbons were studied by the DSC method in the mode of continuous heating. The apparent activation energy Ep1 and Ep2 (373.07±7.92 and 518.75±21.35 kJ/mol, respectively) derived from the Kissinger plots were calculated by the peak temperatures Tp1, Tp2, which display a strong dependence on the heating rates. The crystallization behavior during isothermal annealing at 823 K for 1, 5, 10 h and 973 K for 5 h were investigated using XRD and TEM. The results show that crystallization behavior becomes completely different from that of FINEMET. It is not bcc α-Fe (Si) but metastable fcc γ-Fe (Si) that participates in the first crystallization step combining the appearance of Fe23B6 and Nb2B. Therefore, the addition of C promotes the combination of Fe and B. Fe3.5B is participated in the second step together with the disappearing of Fe23B6, which indicates that transition Fe23B6→Fe3.5B+Fe2B presumably happens. γ-Fe (Si) with peculiar stability cannot transform into nano-sized α-Fe (Si) crystals until the amorphous ribbons were annealed for 5 h at 973 K.
关键词:
Amorphous
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null
,
null
,
null
Zhaoxia PING
,
Juntao YUAN
,
Yedong HE
,
Xiaogang LI
金属学报(英文版)
doi:10.1016/S1006-7191(08)60093-9
A mechanically assisted electroless barrel-plating Ni-P was carried out in a rolling drum containing Mg alloy specimens and ceramic balls, which was submerged in a bath containing electroless plating solution. It is demonstrated that the Ni-P coatings deposited by this novel technique have a crystallized Ni-P solid solution structure, showing fine-grains, higher hardness, and higher corrosion resistance compared with the conventional electroless plated amorphous Ni-P coatings. After heat treatment at 400℃ for 1 h, the structure of such Ni-P coatings were transformed to a structure with Ni-Ni3P double phases, and cracks in these coatings could not be observed, whereas cracks appeared seriously in the conventional electroless plated Ni-P coating after same heat treatment. Therefore, both hardness and corrosion resistance of these Ni-P coatings can be improved further by heat treatment. All of these beneficial effects can be attributed to the role of mechanical attrition during the mechanically assisted electroless barrel-plating process.
关键词:
Mechanically assisted electroless barrel-plating
,
null
,
null
,
null
,
null
隋普辉
,
陆雷
宇航材料工艺
doi:10.3969/j.issn.1007-2330.2009.06.009
采用DTA、XRD、SEM等分析了锂锌铝硅(LZAS)系微晶玻璃的析晶及热学和力学性能.结果表明:610℃时析出晶体γ_Ⅱ-LZS,为0.2μm的树枝状;650℃时出现直径为0.5μm的球状方石英晶粒,随后晶粒消失;720℃之后开始析出蜂窝状网络结构β-石英固溶体,并且γ_Ⅱ-LZS逐渐转化为γ_0-LZS晶体;8500C时β-石英固溶体转变为均匀的颗粒状β-锂辉石固溶体,直径为1 μm.试样的线胀系数随晶化温度先增大再减小后趋于平稳,而试样的弯曲强度先减小再增大后趋于平稳,其变化规律依赖于晶化过程中产生的晶相的种类以及含量.
关键词:
微晶玻璃
,
析晶
,
线胀系数
,
弯曲强度
陈慧余
,
张道元
,
王昌燧
,
卢国荣
,
兰志刚
金属学报
用X射线衍射、吸收和内转换电子发射Mossbauer谱技术,研究了Fe_(80-x)Cu_xSi_5B_(15)和(Fe_(1-y)Co_y)_(82)Cu_(0.4)Si_(4.4)B_(13.2)两系列非晶合金的晶化行为.单辊急冷法制备的非晶带,晶化首先从贴辊面开始,晶化产物为α-Fe相.在Fe_(80)Si_5B_(15)非晶合金中以少量Cu替代Fe可以提高晶化温度.我们的结果表明,过渡金属的含量超过80at.-％,如增加到82at.-％,晶化温度就明显降低.所研究两系列含Si的铁基非晶合金在400—450℃范围内退火2h,都出现α-Fe,Fe_3B和Fe_2B三种晶态相共存状态.退火温度再升高,亚稳相Fe_3B逐渐转变为Fe_2B和α-Fe.
关键词:
晶化
,
amorphous alloy
,
crystalline phase
,
coexistence
Bin TANG
,
Xinqiang YUAN
,
Tianfeng XUE
,
Jiacheng LI
,
Youyu FAN
材料科学技术（英文）
Crystallization behavior of the glass system AlF3-MgF2-CaF2-SrF2-BaF2-YF3-TeO2 (AMCSBY-TeO2) was studied by the nonisothermal method using differential thermal analysis. The activation energy E and Avrami exponent $n$ were determined by nonisothermal method. It is found that the value of E varies with increasing TeO2 and reaches a minimum at 10~mol~fraction TeO2, while n decreases from 3.65 to 1.78 with the addition of TeO2. X-ray diffraction shows that Ba2Te3O8, MgTe2O5, and SrTeO3 phase formed when the glasses were reheated. The addition of TeO2 changes the crystallization mechanism and improves the stability of the fluoroaluminate glass.
关键词:
Fluoroaluminate glass
,
TeO2
,
析晶
