The influence of chemistry on the interface toughness in a WTi-Cu system

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With a considerable amount of commonly used material systems consisting of individual, rather confined layers, the question for mechanical behaviour of their individual interfaces arises. Especially, when considering varying interfacial structures as a result of the processing environment. Furthermore, the interaction between pronounced plasticity and fracture processes can lead to challenges with regards to separation between sole interface- or bulk properties.

The present work investigates the interfacial fracture characteristic of a WTi-Cu sytem commonly found in the microelectronics industry as a heterogeneous model material with pronounced plasticity in the Cu phase. To study this behaviour on a rather limited scale (<6 µm), microcantilever experiments were conducted and evaluated using a continuous J-Δa curve evaluation scheme with classical elastic-plastic considerations in mind. A change in interface chemistry, resulting from air exposure between processing steps, was probed and found to show distinct crack propagation along the interface opposed to crack tip blunting as encountered in the vacuum processed sample. Complementary density functional theory calculations also showed a strong reduction of interface cohesion upon oxygen accumulation and a model framework based on classical dislocation plasticity considerations revealed the transition from plasticity to fracture processes to be a result of shielding and following change in mode mixity.
FachzeitschriftActa Materialia
Ausgabenummer15 May
Frühes Online-Datum5 März 2022
PublikationsstatusVeröffentlicht - 15 Mai 2022

Bibliographische Notiz

Funding Information:
The authors gratefully acknowledge the financial support under the scope of the COMET program within the K2 Center “Integrated Computational Material, Process and Product Engineering, IC-MPPE” (Projects A2.12). This program is supported by the Austrian Federal Ministries for Transport, Innovation and Technology (BMVIT) and for Digital and Economic Affairs (BMDW), represented by the Österreichische Forschungsförderungsgesellschaft (Funder ID: 10.13039/501100004955 ), and the federal states of Styria, Upper Austria, and Tyrol. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant No. 771146 TOUGHIT ).

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