A fractographic study of hydrogen-assisted cracking and liquid-metal embrittlement in nickel
A fractographic study of hydrogen-assisted cracking and liquid-metal embrittlement in nickel
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镍氢辅助裂解和液态金属脆化的断口研究
DOI：
10.1007/bf01145543
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发表时间：
1986
影响因子：
4.5
通讯作者：
S. Lynch
中科院分区：
文献类型：
--
作者：
S. Lynch
描述了多种环境下镍多晶和单晶裂纹扩展的金相和断口研究。在液态汞、液态锂、液态钠、气态氢中测试的试件，以及在空气中测试的充氢试件，观察到“脆性”晶间和穿晶解理样断口。脆性断裂伴随着相当大的滑移，在断口上观察到韧窝/撕裂脊，这表明裂纹的扩展是通过局部塑性流动进行的。吸附诱导的液态金属脆化与氢助开裂有显著的相似之处，与其他观察结果一起，表明裂纹尖端的吸附氢是氢助开裂的原因。结果表明，吸附原子削弱了裂纹尖端的原子间键，从而促进了位错的形核，并通过局部塑性流动促进了裂纹的扩展。
Metallographic and fractographic studies of crack growth in nickel polycrystals and single crystals in a number of environments are described. “Brittle” intercrystalline and transcrystalline cleavage-like fractures were observed for specimens tested in liquid mercury, liquid lithium, liquid sodium, gaseous hydrogen, and for hydrogen-charged specimens tested in air. “Brittle” fractures were associated with considerable slip, and dimples/tear ridges were observed on fracture surfaces, suggesting that crack growth occurred by localized plastic flow. There were remarkable similarities between adsorption-induced liquid-metal embrittlement and hydrogen-assisted cracking which, along with other observations, suggested that adsorbed hydrogen at crack tips was responsible for hydrogen-assisted cracking. It is concluded that adsorbed atoms weaken interatomic bonds at crack tips thereby facilitating the nucleation of dislocations and promoting crack growth by localized plastic flow.