材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
論文
自立金属ナノ薄膜のその場電界放射走査型電子顕微鏡観察疲労/クリープ強度試験法の開発
近藤 俊之秦 彰宏平方 寛之﨑原 雅之箕島 弘二
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ジャーナル フリー

2016 年 65 巻 12 号 p. 869-876

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Experimental technique of in situ FESEM fatigue/creep experiments has been developed to investigate the mechanisms of fatigue/creep crack propagation in freestanding metallic nano-films. We developed an in situ FESEM fatigue/creep dual-mode testing machine which was able to conduct the fatigue or creep experiments inside the FESEM chamber. The testing machine has the capability to apply high-frequency cyclic load or constant load under load-control conditions to the freestanding metallic nano-film specimens. In situ FESEM observations of the fatigue crack propagation in 523-nm-thick freestanding copper (Cu) films confirmed that intrusions/extrusions were formed ahead of the fatigue crack tip in the lower stress intensity factor range (ΔK), and the size of the intrusions/extrusions increased as the number of stress cycles increased. The fatigue crack then propagated preferentially through these intrusions/extrusions. In the higher ΔK, the fatigue crack propagated in tensile fracture mode. In addition, in situ FESEM observations of the creep crack propagation in 391-nm-thick freestanding gold (Au) films confirmed that voids were formed ahead of the creep crack tip, and the crack then propagated by coalescence of the voids and the crack. These results indicate that this experimental technique is effective to clarify the mechanisms and mechanics of fatigue/creep crack propagation in freestanding nano-films.

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