Helium in Cu-Ag-Fe triphase immiscible nanocomposites: An in situ sequential dual beam TEM study

Helium (He) generated during irradiation is notorious for inducing volumetric swelling and grain bound-ary embrittlement. It is imperative to design advanced materials with effective capability to manage He. Here, we report a largelydifferent bubble swelling behavior in Cu50Ag50, Cu45Ag45Fe10 and Cu33Ag33Fe34 nanocomposites with similar grain sizes. In situ He pre-injection leads to similar He bubble size and den-sity in all three alloy systems. After subsequent Kr irradiation, the average bubble size and swelling in Cu33Ag33Fe34 is much less than Cu50Ag50. Additionally, while bubble size is much greater along triple junctions and grain boundaries than in matrix in Cu50Ag50, the bubble size at the triple junctions in Cu33Ag33Fe34 is much less, suggesting the vital role of Cu-Ag-Fe triphase triple junctions and phase boundaries in managing He. The present study provides new perspective for improving the radiation tolerance of nanocrystalline alloys by microstructure design.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

A study found that helium bubble swelling can be effectively controlled by pre-injecting helium in Cu50Ag50, Cu45Ag45Fe10, and Cu33Ag33Fe34 nanocomposites, with Cu33Ag33Fe34 exhibiting smaller bubble swelling compared to Cu50Ag50. This suggests the vital role of Cu-Ag-Fe triphase triple junctions and phase boundaries in managing helium. The study provides a new perspective for improving the radiation tolerance of nanocrystalline alloys through microstructure design.