共查询到18条相似文献,搜索用时 93 毫秒
1.
2.
3.
本文研究了Pd40Ni40P20块状非晶在4 GPa及常压下的晶化过程。得到了时间-温度转变图。结果表明:高压下样品的晶化温度明显升高,压力对原子的长程扩散及相分离熔体的粘性流动均有抑制作用。在接近熔点进行高压退火时,获得了单相过饱和固溶体。其晶体结构为面心立方。 相似文献
4.
采用静态拉伸方法在连续升温条件下动态地测量了大块金属玻璃Zr41Ti14Cu12.5Ni10Be22.5(Vit1)的黏度随温度的变化关系.在应变速率与温度的关系曲线中,观测到了与玻璃转变和晶化过程相联系的多个应变速率峰.在玻璃转变温度Tg以上,大块金属玻璃Zr41Ti14Cu12.5Ni10Be22.5的过冷液体呈现Newton流体特征,其黏度与温度的关系符合Vogel Fulcher-Tammann (VFT)关系式,拟合得到脆度D*=36,VFT温度T0=319K,脆度参数m=30,这说明Zr41T
关键词:
大块金属玻璃
应变速率
剪切黏度
自由体积 相似文献
5.
采用静态拉伸方法在连续升温条件下动态地测量了大块金属玻璃Zr41 Ti14Cu12.5Ni10Be225(Vitl)的黏度随温度的变化关系.在应变速率与温度的关系曲线中,观测到了与玻璃转变和晶化过程相联系的多个应变速率峰.在玻璃转变温度Tg以上,大块金属玻璃Zr41Ti14Cu125Ni10Be225的过冷液体呈现Newton流体特征,其黏度与温度的关系符合Vogel-Fulcher-Tammann(VFT)关系式,拟合得到脆度D*=36,VFT温度T0=319K,脆度参数m=30,这说明Zr41 Ti14Cu12.5Ni10Be225的过冷液体是一种类似于硅酸盐类的"强"液体.在玻璃转变温度Tg以下,粘度与温度的关系偏离VFT关系,从结构弛豫的观点出发,借助金属玻璃的自由体积模型对其进行了分析和讨论. 相似文献
6.
7.
本文研究了Fe40Ni40P12B8非晶合金冲击波加载下的晶化行为,冲击波由二级轻气炮发射的告诉弹丸撞击靶产生。实验结果表明:Fe40Ni40P12B8非晶合金在冲击波加载下,晶化可在加载时间(微秒量级)内发生;晶化的阈值压力在30~50 GPa之间,相应的冲击温度约为510~800 K,晶化析出相与冲击压力有关,低压下析出相是面心立方γ-(Fe, Ni)固溶体和Fe3(P0.37B0.63)化合物,高压下(大于60 GPa)析出相除了面心立方γ-(Fe, Ni)固溶体和Fe3(P0.37B0.63)化合物之外,还包括(Fe, Ni)3P化合物。 相似文献
8.
9.
10.
11.
LI Gong ZHAN Zaiji LIU Jing YUN Jinku SUN Liling LIU Riping ZHANG Jun & WANG Wenkui . Key Laboratory of Metastable Materials Science Technology Yanshan University Qinhuangdao China . Center for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing China . BSRF Institute of High Energy Physics Chinese Academy of Sciences Beijing China 《中国科学G辑(英文版)》2005,48(3)
With the development of multicomponent Zr-based glass bulk metallic glasses(BMGs) with a larger geometry by a conventional casting process with a low coolingrate[1—4], high pressure, which is the simplest way to vary the interatomic distance ofsubstance and thus change its physical properties, has been employed as an importantmeans to investigate structural relaxation and the crystallization of the BMGs[5]. Relativeto crystalline, metallic glasses have excess free volume, which will annihil… 相似文献
12.
Zr41Ti14Cu12.5Ni10Be22.5bulk metallic glass (BMG) is annealed at 573 K under 3 GPaand its structural relaxation is investigated by X-ray diffraction, ultrasonic study, compression as well as sliding wear measurements. It is found that after the ZrTiCuNiBe BMG sample was annealed under high pressure, the mechanical properties were improved. Moreover, the BMG with relaxed structure exhibits markedly different acoustic properties. These results are attributed to the fact that relaxation under high-pressure results in a microstructural transformation in the BMG. 相似文献
13.
14.
采用分子动力学的方法模拟Zr_(67)Ni_(33)合金液体在不同压强下快速凝固过程,通过结构分析方法如对分布函数、配位数、Honeycutt-Andersen(HA)键型指数法,以及动力学参数如均方位移、自散射关联函数、非高斯参数研究压强对Zr_(67)Ni_(33)非晶合金局域原子结构和其过冷液体动力学性能的影响.研究结果表明:压强越大,Zr_(67)Ni_(33)非晶合金中Zr-Ni原子间的相互作用越强,体系结构有序性越强,过冷液体中动力学减慢和动力学不均匀现象越显著. 相似文献
15.
The compression of a Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) is investigated at room temperature up to 24 GPa using in-situ high pressure energy dispersive
X-ray diffraction with a synchrotron radiation source. The pressure-induced structural relaxation is exhibited. It is found
that below about 8 GPa, the existence of excess free volume contributes to the rapid structural relaxation, which gives rise
to the rapid volumetric change, and the structural relaxation results in the structural stiffness under higher pressure. 相似文献
16.
The present paper considers the formation of crystalline phases during solidification and crystallisation of the Zr53Cu21Al10Ni8Ti8 alloy. Solidification was carried out by a copper mould casting technique, which yielded a partially crystalline microstructure comprising a ‘big cube phase’ in a dendritic morphology and a bct Zr2Ni phase. Detailed high-resolution microscopy was carried out to determine possible mechanisms for the formation of the crystalline phases. Based on microstructural examinations, it was established that the dendrites grew by the attachment of atomistic ledges. The bct Zr2Ni phase, formed during solidification and crystallisation, showed various types of faults depending on the crystallite size, and its crystallography was examined in detail. It has been shown that the presence of these faults could be explained by anti-site occupancy in the bct lattice of the Zr2Ni phase. 相似文献
17.
Free volume and medium-range order (MRO) present in rapidly solidified ribbons (RSRs) and bulk metallic glasses (BMGs) of Zr52Ti6Al10Cu18Ni14 have been probed by high resolution electron microscopy, fluctuation microscopy, positron annihilation and differential scanning calorimetry. In the as-solidified condition, RSRs showed higher free volume and lower MRO in comparison to BMGs. Within BMGs, the central regions showed higher MRO and lower free volume than the peripheral regions. Uniform deformation of BMGs and RSRs modified their structures, where in, free volume increased in the former and reduced in the latter. These changes in structures led to work hardening in RSRs and work softening in BMGs. Such behaviour could be explained by invoking a concept of critical free volume in the glass phase. For samples (in as-solidified condition) having free volume higher than the critical value, free volume decreased with deformation and showed work-hardening behaviour. In contrast, the work softening behaviour was noticed in samples having free volume lower than the critical free volume. 相似文献
18.
Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) is annealed at 573 K under 3 GPa and its structural relaxation is investigated by X-ray diffraction,
ultrasonic study, compression as well as sliding wear measurements. It is found that after the ZrTiCuNiBe BMG sample was annealed
under high pressure, the mechanical properties were improved. Moreover, theBMG with relaxed structure exhibits markedly different
acoustic properties. These results are attributed to the fact that relaxation under high-pressure results in a microstructural
transformation in the BMG. 相似文献