Pd—Eu合金内氧化

INTERNAL OXIDATION OF Pd-Eu ALLOYS

Pd—Eu合金在氧化性气氛中退火时,活性溶质Eu发生内氧化,形成稳定氧化物Eu_2O_3内氧化是由扩散机制控制的Eu_2O_3形核长大过程:氧通过体扩散和晶界扩散进入合金内,Eu由内层扩散到外层研究了内氧化动力学对于圆截面试样,内氧化层深度(ξ)与氧化时间(t)满足公式ξ=Kt^n当温度800—900℃时,n=0.5,符合抛物线规律;当温度高达1200℃时,n=0.75,偏离抛物线规律PdEu0.

The internal oxidation of active solute Eu in Pd-Eu alloys has been studied in air at 800--1200℃. It was a nucleation and growing process of stable oxide Eu_2O_3 controlled by diffusion mechanism: oxygen entered to internal layer and Eu diffused towards outer layer and surface through bulk and grain boundary diffusion, this caused non-homogeneous dis- tribution of oxygen and Eu. For wire samples with dia. 2mm, the dependence of the internal oxidation depth (ξ) on the reaction time (t) could be expressed as ξ= Kt^n, here n=0.5 at 800-- 900℃, and n=0.75 at 1200℃. The activation energy of Pd-0.56at.-%Eu alloy was deter- mined to be 150 kJ/mol.