Thermal properties and glass-forming ability of bulk glassy alloys

Pd基和Zr基玻璃态合金具有很宽的过冷液相区，这是众所周知的。这些大块非晶合金使我们能够研究这些合金的热性能和电阻率。本工作的主要目的是讨论这些合金的玻璃形成能力的基础上获得的值。用激光闪光技术测量了合金的热扩散率值。通过直流四探针技术测量电阻率。比热通过具有三电池系统的热通量型差示扫描量热计测量。合金在液态下的热扩散率值被概括为具有正温度依赖性的线性方程。合金在液相线温度下的热扩散率越低，获得非晶合金的临界冷却速率就越低。因此，合金液体的热扩散率值可能是其玻璃形成能力的指标。Zr_<55>Al_<10>Ni_5Cu_<30>合金的热扩散系数在玻璃态下具有正的温度依赖性。合金的热扩散系数在晶化温度（Tc）处突然增大。在晶化温度范围内，热扩散系数随温度的升高逐渐增大，呈现出三个阶段。电阻率值在Tc处突然减小，并逐渐减小，表现出与热扩散率值相同的趋势。测<55><10><30>得玻璃态Zr_Al_Ni_5Cu_3的比热为0.372 μ g·<-1>K ~（-1）<-1>。还获得了液态Pd基合金的比热值。这些值显示出小的负温度依赖性。根据Wiedemann-Franz定律分析，Pd基合金在过冷液态和液态下的主要机制可能是电子控制。

Pd-based and Zr-based glassy alloys are well known to exhibit glass transition with a wide supercooled liquid region. These bulk amorphous alloys allow us to investigate thermal properties and electrical resistivity of these alloys. The main purpose of this work is to discuss the glass-forming ability of these alloys on the basis of the obtained values. The thermal diffusivity values of the alloys were measured with a laser flash technique. The electrical resistivity was measured by a direct current four probe technique. The specific heat was measured by the heat flux type differential scanning calorimeter with a triple cell system. The thermal diffusivity values of the alloys in the liquid state are summarized in the linear equations with positive temperature dependency. The lower the thermal diffusivity values of the alloys at liquidus temperature, the lower the critical cooling rate to obtain amorphous alloy becomes. Thus, the thermal diffusivity values of alloy liquids might be an indicator of their glass forming ability. The thermal diffusivity values of Zr_<55>Al_<10>Ni_5Cu_<30> alloy show positive temperature dependence in the glassy state. The thermal diffusivity values of the alloy increase suddenly at crystallization temperature (Tc). The thermal diffusivity values increase gradually showing three stages in the crystallization temperature range with increasing temperature. The electrical resistivity values suddenly decrease at Tc and gradually decrease showing same tendency of the thermal diffusivity values. The specific value of Zr_<55>Al_<10>Ni_5Cu_<30> in the glass state was measured to be 0.372 Jg^<-1>K^<-1>. The specific heat values for liquid Pd-based alloys were also obtained. These values show small negative temperature dependence. It was also suggested from analysis with Wiedemann Franz law that principal mechanism of Pd-based alloy is likely to be controlled by electron in the super cooled liquid and liquid states.