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Analiza struktury złącza PA38/AZ31 wytworzonego metodą zgrzewania dyfuzyjnego

Mola R., Cieślik M., Bartos J.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

2018

z. 90 [298], nr 3

367--376

W artykule przedstawiono analizę struktury złącza stop aluminium (PA38)–stop magnezu (AZ31) wytworzonego metodą zgrzewania dyfuzyjnego. Za pomocą mikroskopu optycznego i elektronowego mikroskopu skaningowego przeprowadzono szczegółowe badania metalograficzne. Skład chemiczny strefy złącza określono metodą mikroanalizy rentgenowskiej (EDS). Wykonano również pomiary mikrotwardości metodą Vickersa łączonych materiałów i strefy złącza. W wyniku procesu zgrzewania uzyskano trwałe połączenie. Strefa złącza, o grubości ok. 50 µm, miała budowę dwuwarstwową. Od strony stopu PA38 w złączu zidentyfikowano grubszą warstwę (ok. 40 µm) fazy międzymetalicznej Al3Mg2, od strony stopu AZ31 cieńszą warstwę (ok. 10 µm) fazy międzymetalicznej Mg17Al12. W mikrostrukturze strefy złącza od strony stopu PA38 na tle osnowy fazy Al3Mg2 stwierdzono obecność drobnych cząstek fazy Mg2Si. Od strony stopu AZ31, na tle fazy Mg17Al12, obserwowano lokalnie iglaste cząstki fazy Al-Mn-Si. Na podstawie pomiarów mikrotwardości stwierdzono, że strefa złącza zbudowana głównie z faz międzymetalicznych Mg-Al charakteryzuje się kilkukrotnie wyższą mikrotwardością w porównaniu z łączonymi stopami.

This paper presents the results of the microstructure investigation of the aluminium alloy (PA38) – magnesium alloy (AZ31) joint fabricated by diffusion bonding. The structure of the bonding zone was examined using optical microscopy and scanning electron microscopy. The chemical composition of the bonding zone was determined by energy dispersive X-ray microanalysis. The microhardness measurements of the alloys and the bonding zone was also conducted. As a result of the diffusion bonding process the alloys were joined together. The bonding zone with a thickness of about 50μm had two-layer structure. In the bonding zone the thicker layer (about 40μm) of Al3Mg2 intermetallic phase was observed on the PA38 alloy side. The thinner layer (about 10 μm) of Mg17Al12 intermetallic phase was observed on the AZ31 alloy side. In the area of the bonding zone close to the PA38 alloy fine particles of Mg2Si phase were found in the matrix of Al3Mg2. In the bonding zone close to the AZ31 alloy locally a needle-shaped particles of the Al-Mn-Si phase were observed over the Mg17Al12 phase matrix. The results of microhardness measurement revealed that the bonding zone composed mainly of Mg-Al intermetallic phases layers had much higher microhardness than the joined alloys.

Characterization of the Bonding Zone in a ZE41/AlSi12 Joint Fabricated by Liquid- Solid Compound Casting

Mola R., Bucki T.

Archives of Foundry Engineering

2018

Vol. 18, iss. 2

203--208

The study involved using the liquid-solid compound casting process to fabricate a lightweight ZE41/AlSi12 bimetallic material. ZE41 melt heated to 660 °C was poured onto a solid AlSi12 insert placed in a steel mold. The mold with the insert inside was preheated to 300 °C. The microstructure of the bonding zone between the alloys was examined using optical microscopy and scanning electron microscopy. The chemical composition was determined through linear and point analyses with an energy-dispersive X-ray spectroscope (EDS). The bonding zone between the magnesium and aluminum alloys was about 250 μm thick. The results indicate that the microstructure of the bonding zone changes throughout its thickness. The structural constituents of the bonding zone are: a thin layer of a solid solution of Al and Zn in Mg and particles of Mg-Zn-RE intermetallic phases (adjacent to the ZE41 alloy), a eutectic region (Mg17(Al,Zn)12 intermetallic phase and a solid solution of Al and Zn in Mg), a thin region containing fine, white particles, probably Al-RE intermetallic phases, a region with Mg2Si particles distributed over the eutectic matrix, and a region with Mg2Si particles distributed over the Mg-Al intermetallic phases matrix (adjacent to the AlSi12 alloy). The microstructural analysis performed in the length direction reveals that, for the process parameters tested, the bonding zone forming between the alloys was continuous. Low porosity was observed locally near the ZE41 alloy. The shear strength of the AZ91/AlSi17 joint varied from 51.3 to 56.1 MPa.