The effect of Pd addition on the glass-forming ability and thermal stability of the Zr5sAl10Cus0Nis-xPdx (x=0, 1, 3,5 at. Pct) alloys upon copper-mold casting has been investigated. The structure, thermal stability an...The effect of Pd addition on the glass-forming ability and thermal stability of the Zr5sAl10Cus0Nis-xPdx (x=0, 1, 3,5 at. Pct) alloys upon copper-mold casting has been investigated. The structure, thermal stability and microstructure were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM), respectively. It was identified that a new bulk amorphous alloy with the larger supercooled liquid region Atx of 100 K is obtained with substituting Ni by 1 at. Pct Pd. Furthermore, the origins that thermal stability and GFA change with increasing of Pd have also beer discussed.展开更多
A new microstructure model is developed for amorphous alloys,so called Cluster medel,in which the amorphous phase is thought of composing of randomly distributed orderedclusters of different sizes.Thermodynamic calcul...A new microstructure model is developed for amorphous alloys,so called Cluster medel,in which the amorphous phase is thought of composing of randomly distributed orderedclusters of different sizes.Thermodynamic calculation on this model deduces a parameterdescribing the glass forming ability of metallic alloys:α_c=(1-2.08/Φ_m)T_g/T_m,whereT_g is gass transition temperature,T_m is the melting temperature,and Φ_m is entralpychange of melting.It is believed that easy glass forming alloy systems have larger valuesof a_c.This new criterion of GFA not only provides the theoretical background for severalGFA criteria in the literature cited,but also can predict the GFA of many alloy systemsmore reasonably and accurately.展开更多
Classical molecular dynamics(MD)were conducted to study the structure and energy distribution of Zr_(x)Cu_(90-x)Al_(10)(x=20,30,40,50,60,70)ternary alloys.When the Zr composition is 30%,the glass transition temperatur...Classical molecular dynamics(MD)were conducted to study the structure and energy distribution of Zr_(x)Cu_(90-x)Al_(10)(x=20,30,40,50,60,70)ternary alloys.When the Zr composition is 30%,the glass transition temperature reaches the maximum value and the Zr_(30)Cu_(60)Al_(10)owns high glass forming ability(GFA).Analysis of the short⁃range structure shows that there are more low⁃energy Zr⁃centered polyhedron with high coordination number(CN)and Cu and Al⁃centered coordination polyhedron with CN=12 in Zr_(30)Cu_(60_Al_(10)alloy.As the medium⁃range structure is concerned,Zr_(30)Cu_(60_Al_(10)alloy has the largest number of coordination polyhedron connection sharing three atoms and connection in this way presenting the lowest energy.These low⁃energy and stable short and medium⁃range structures contribute to the high GFA of Zr_(30)Cu_(60_Al_(10).展开更多
基金The authors are grateful to the financial support by the National Key Basic Research and Development Program of China(No.G200067201)National High Technical Research Development Program of China(No.2001AA331010)for this research.
文摘The effect of Pd addition on the glass-forming ability and thermal stability of the Zr5sAl10Cus0Nis-xPdx (x=0, 1, 3,5 at. Pct) alloys upon copper-mold casting has been investigated. The structure, thermal stability and microstructure were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM), respectively. It was identified that a new bulk amorphous alloy with the larger supercooled liquid region Atx of 100 K is obtained with substituting Ni by 1 at. Pct Pd. Furthermore, the origins that thermal stability and GFA change with increasing of Pd have also beer discussed.
文摘A new microstructure model is developed for amorphous alloys,so called Cluster medel,in which the amorphous phase is thought of composing of randomly distributed orderedclusters of different sizes.Thermodynamic calculation on this model deduces a parameterdescribing the glass forming ability of metallic alloys:α_c=(1-2.08/Φ_m)T_g/T_m,whereT_g is gass transition temperature,T_m is the melting temperature,and Φ_m is entralpychange of melting.It is believed that easy glass forming alloy systems have larger valuesof a_c.This new criterion of GFA not only provides the theoretical background for severalGFA criteria in the literature cited,but also can predict the GFA of many alloy systemsmore reasonably and accurately.
文摘Classical molecular dynamics(MD)were conducted to study the structure and energy distribution of Zr_(x)Cu_(90-x)Al_(10)(x=20,30,40,50,60,70)ternary alloys.When the Zr composition is 30%,the glass transition temperature reaches the maximum value and the Zr_(30)Cu_(60)Al_(10)owns high glass forming ability(GFA).Analysis of the short⁃range structure shows that there are more low⁃energy Zr⁃centered polyhedron with high coordination number(CN)and Cu and Al⁃centered coordination polyhedron with CN=12 in Zr_(30)Cu_(60_Al_(10)alloy.As the medium⁃range structure is concerned,Zr_(30)Cu_(60_Al_(10)alloy has the largest number of coordination polyhedron connection sharing three atoms and connection in this way presenting the lowest energy.These low⁃energy and stable short and medium⁃range structures contribute to the high GFA of Zr_(30)Cu_(60_Al_(10).
