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Evolution of the interfacial phases in Al2O3–Kovar® joints brazed using a Ag–Cu–Ti-based alloy
| Content Provider | Scilit |
|---|---|
| Author | Ali, Majed Knowles, Kevin M. Mallinson, Phillip M. Fernie, John A. |
| Copyright Year | 2017 |
| Description | A systematic investigation of the brazing of $Al_{2}O_{3}$ to $Kovar^{®}$ (Fe–29Ni–17Co wt.%) using the active braze alloy (ABA) Ag–35.25Cu–1.75Ti wt.% has been undertaken to study the chemical reactions at the interfaces of the joints. The extent to which silica-based secondary phases in the $Al_{2}O_{3}$ participate in the reactions at the $ABA/Al_{2}O_{3}$ interface has been clarified. Another aspect of this work has been to determine the influence of various brazing parameters, such as the peak temperature, $T_{p}$, and time at $T_{p}$, τ, on the resultant microstructure. As a consequence, the microstructural evolution of the joints as a function of $T_{p}$ and τ is discussed in some detail. The formation of a $Fe_{2}$Ti layer on the $Kovar^{®}$ and its growth, along with adjacent $Ni_{3}$Ti particles in the ABA, dominate the microstructural developments at the $ABA/Kovar^{®}$ interface. The presence of $Kovar^{®}$ next to the ABA does not change the intrinsic chemical reactions occurring at the $ABA/Al_{2}O_{3}$ interface. However, the extent of these reactions is limited if the purity of the $Al_{2}O_{3}$ is high, and so it is necessary to have some silica-rich secondary phase in the $Al_{2}O_{3}$ to facilitate the formation of a $Ti_{3}Cu_{3}$O layer on the $Al_{2}O_{3}$. Breakdown of the $Ti_{3}Cu_{3}$O layer, together with fracture of the $Fe_{2}$Ti layer and separation of this layer from the $Kovar^{®}$, has been avoided by brazing at temperatures close to the liquidus temperature of the ABA for short periods of time, e.g., for $T_{p}$ between 820 and 830 °C and τ between 2 and 8 min. |
| Related Links | https://www.repository.cam.ac.uk/bitstream/1810/291343/1/3cusilabakov.pdf |
| Ending Page | 742 |
| Page Count | 25 |
| Starting Page | 718 |
| ISSN | 14786435 |
| e-ISSN | 14786443 |
| DOI | 10.1080/14786435.2016.1275868 |
| Journal | Philosophical Magazine |
| Issue Number | 10 |
| Volume Number | 97 |
| Language | English |
| Publisher | Informa UK Limited |
| Publisher Date | 2017-04-03 |
| Access Restriction | Open |
| Subject Keyword | Legal Medicine Brazing Joining Alumina Cusil Aba |
| Content Type | Text |
| Resource Type | Article |
| Subject | Condensed Matter Physics |
