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首页> 外文会议>Symposium on Actinides - Basic Science, Applications and Technology; 20031201-20031203; Boston,MA; US >'Burst-like' Characteristics of the δ/α′ Phase Transformation in Pu-Ga Alloys
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'Burst-like' Characteristics of the δ/α′ Phase Transformation in Pu-Ga Alloys

机译：Pu-Ga合金中δ/α′相变的“类爆”特征

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摘要

The δ to α′ phase transformation in Pu-Ga alloys is intriguing for both scientific and technological reasons. On cooling, the ductile fcc δ-phase transforms martensitically to the brittle monoclinic α′-phase at approximately -120℃ (depending on composition). This exothermic transformation involves a 20% volume contraction and a significant increase in resistivity. The reversion of α′ to δ involves a large temperature hysteresis and begins just above room temperature. In an attempt to better understand the underlying thermodynamics and kinetics responsible for these unusual features, we are examining the δ/α′ transformations in a Pu-0.6 wt% Ga alloy using differential scanning calorimetry (DSC) and resistometry. Both techniques indicate that the martensite start temperature is -120℃ and the austenite start temperature is 35℃. The heat of transformation is approximately 3 kJ/mole. During the α′ → δ reversion, "spikes" and "steps" are observed in DSC and resistometry scans, respectively. These spikes and steps are periodic, and their periodicity with respect to temperature does not vary with heating rate. With an appropriate annealing cycle, including a "rest" at room temperature, these spikes and steps can be reproduced through many thermal cycles of a single sample.
机译：出于科学和技术方面的原因，Pu-Ga合金中的δ至α'相变令人着迷。冷却后，易延展的fccδ相在约-120℃下马氏体转变为脆性单斜晶α'相（取决于成分）。这种放热转变涉及20％的体积收缩和电阻率的显着提高。 α'转换为δ涉及较大的温度滞后，并且刚好在室温以上开始。为了更好地理解造成这些异常特征的潜在热力学和动力学，我们正在使用差示扫描量热法（DSC）和电阻法研究Pu-0.6 wt％Ga合金中的δ/α'相变。两种技术都表明马氏体的起始温度为-120℃，奥氏体的起始温度为35℃。转化热约为3kJ /摩尔。在α'→δ还原期间，分别在DSC和电阻法扫描中观察到“尖峰”和“台阶”。这些峰值和阶跃是周期性的，并且它们相对于温度的周期性不随加热速率而变化。通过适当的退火循环，包括在室温下的“静止”，可以通过单个样品的许多热循环来复制这些尖峰和台阶。

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