Interfacial fracture behavior of tungsten wire/tungsten matrix composites with copper-coated interfaces

Abstract

Order of Authors: Juan Du, MSc.; Till Höschen1, Dipl.-Ing.; Marcin Rasinski, MSc.; Jeong-Ha You, Dr.-Ing.Abstract: The potential application of tungsten as a structural material has been strongly restricted by inherent brittleness. The hitherto metallurgical efforts to improve tungsten toughness seem to be still less matured. The authors have been exploring a novel toughening technique based on reinforcement by tungsten wires. Toughness is supposed to be enhanced through the energy dissipation at the wire/matrix interfaces which is caused by the controlled crack deflection and friction. In this work, we focus on two kinds of copper coatings for interface engineering, namely, copper mono-layer and copper/tungsten multi-layer. Single filament composites were fabricated using magnetron sputtering and CVD process. The interfacial parameters were identified by means of fiber push-out test and microscopic fracture features were investigated. In this paper the results from the extensive push-out experiments are presented together with the fractographs. Finite element simulation was also carried out to estimate the plastic strain of the copper layer. Essential role of the significant plastic deformation in the overall failure behavior is highlighted.Response to the reviewers Reviewer1.The text paragraph was revised according to the reviewer's recommendation (many thanks).The corresponding references were updated [1, 2] and replaced [4]. Reviewer2.1) The manufacturing of the many filament bulk W/W composite materials is a current Ph.D thesis topic of one of my students (since 1 year). This highly challenging study treats the processing development including compaction.2) A direct quantitative comparison of the dissipated energy was added in page 6 line 9-12.3) Still we could not give a general statement about the correlation between ductility of the interface and shear strength, because our experimental result was obtained only for specific ad hoc case of Cu and Cu/W coating layers. We were not sure if metallurgical effects (bonding, wetting, roughness etc.) would have possibly played a more dominant role than the continuum mechanical factors. Figure 5 was improved. Figure 1 was explained in detail. 4) 5) All English corrections were made (many thanks).Response to the editor The mathematical equation was re-typed in according to the instruction. The revised text parts were marked in blue color. AbstractThe potential application of tungsten as a structural material has been strongly restricted by inherent brittleness. The hitherto metallurgical efforts to improve tungsten toughness seem to be still less matured. The authors have been exploring a novel toughening technique based on reinforcement by tungsten wires. Toughness is supposed to be enhanced through the energy dissipation at the wire/matrix interfaces which is caused by the controlled crack deflection and friction. In this work, we focus on two kinds of copper coatings for interface engineering, namely, copper single-layer and copper/tungsten multi-layer. Single ...

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“…These parameters were calibrated by means of numerical regression using the theoretical equations of selected shear-lag models (cf. Appendix) [17,18]. …”

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