Xiaoying CHENG
,
Xiaojing WAN
,
Qiuyun WU
,
Xiukui SUN
材料科学技术（英）
The diffusivity of hydrogen in two Ni3Al alloys (No.1 and No.2) has been measured in the temperature range of 100℃ to 420℃ using an ultrahigh vacuum gaseous permeation technique. The diffusivity data fall into two segments, in which the hydrogen diffusivity adheres to the Arrhenius form, respectively. From the hydrogen diffusivity, it is conjectured that the hydrogen diffusivity reflects the hydrogen transportation along the grain boundaries at lower temperature and the hydrogen transportation in the lattice at higher temperature. The intergranular fracture of Lit-type intermetallics induced by hydrogen at relative low temperature results from hydrogen transportation along the grain boundaries and not in the lattice.
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Xiaoying CHENG
,
Xiaojing WAN
,
Yexin CHEN
,
Meiyi YAO
材料科学技术（英）
Some observation relating tp the solubility, diffusivity and intergranular cracking by hydrogen transport from the external surface in Co3Ti, Co3Ti-Al and Co3Ti-Fe alloys have been carried out. The results show that the addition of alloying elements Al or Fe to Co3Ti alloy can increase the critical hydrogen concentration for changing from transgranular to brittle intergranular fracture, therefore suppress the moisture induced environmental embrittlement.
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