Microstructure and phase transformations in a liquid immiscible Fe 60 Cu 20 P 10 Si 5 B 5 alloy Krzysztof Ziewiec a, * , Miroslawa Wojciechowska a , Grzegorz Garzel b , Tomasz Czeppe b , Artur Blachowski c , Krzysztof Ruebenbauer c a Institute of Technology, Pedagogical University of Cracow, Podchora ˛ _ zych 2, 30 084 Krak ow, Poland b Institute of Metallurgy and Materials Science of Polish Academy of Sciences, Reymonta 25, 30 059 Krak ow, Poland c M€ ossbauer Spectroscopy Division, Institute of Physics, Pedagogical University, Podchora ˛ _ zych 2, 30 084 Krak ow, Poland article info Article history: Received 20 July 2015 Received in revised form 16 September 2015 Accepted 17 October 2015 Available online xxx Keywords: Metallic glasses Microstructure Segregation Differential scanning calorimetry Scanning electron microscopy M€ ossbauer spectroscopy abstract This work presents a study of the microstructure formed in a liquid immiscible Fe 60 Cu 20 P 10 Si 5 B 5 alloy during moderate cooling on a copper plate and melt-spinning. The alloy ingot was re-melted on a copper plate and observed while cooling using a mid-wave infra-red (MWIR) camera. The heating and cooling characteristics of the melt-spun ribbon were studied using differential scanning calorimetry (DSC). The morphology and chemical composition of the ingot as well as the melt-spun ribbon were analyzed using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The compositions of the ingot and the ribbon were investigated using X-ray diffraction (XRD). M€ ossbauer spectroscopic mea- surements showing the influence of adding Cu to the FeeSiePeB alloy were also analyzed. The IR images from the MWIR camera enabled direct observation and identification of the liquid state transformations of the alloy. The DSC trace of the melt-spun ribbon showed crystallization of the amorphous matrix and confirmed that high temperature transformations occurred when the alloy was in the liquid state. Observations of the microstructure of the ingot revealed crystalline surface fractal structures formed by the Fe-rich eutectic constituent and Cu-rich fcc spherical precipitates. The morphology of the precipitates indicated that the precipitates formed in the miscibility gap. The microstructure of the melt-spun ribbon is composed of an amorphous Fe-rich matrix and elongated Cu- rich fcc precipitates. The observations based on the study of the microstructure are supported by M€ ossbauer spectroscopy. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Liquid immiscibility could be an interesting concept to explore when considering the issue of controlling the microstructure of composite materials. It is well known that liquid immiscible alloys such as AlePb, AleBi and CuePb are potential materials for advanced bearings in the automotive industry. There are recent reports on the formation of two-phased glassy composites in an NieNbeY system [1,2],YeTieAleCo system [3], AlePbeNieYeCo system [4], iron-based FeeCueNieSieSneBeY system [5], FeeCueNiePeSieB system [6,7] and FeeCuePeSieB [8] amor- phous/crystalline composite. In the latter alloys, it has been shown that the morphology of the composites can be changed by varying the temperature prior to ejection. Phase transformations and structure development in alloys processed in the liquid state are important for controlling the final microstructure and properties of the alloys, and as such, should be better investigated and understood. Up to this time, the only re- ports on liquid immiscibility in metal alloys were based on ther- mocouple [9], pyrometer [10,11], differential thermal analysis (DTA) [12] and DSC [13,14] measurements. In Ref. [8], the studies of the Fe 60 Cu 20 P 10 Si 5 B 5 amorphous/crystalline alloy prove that its microstructure depends on the temperature of ejection from the crucible, and that the temperature at which the liquid separates can be found using indirect pyrometric and DTA measurements. This present work provides further evidence for this through direct observation of thermal images made by a MWIR camera. These images are verified by DSC analysis and microstructural studies using SEM/EDS and XRD. FeePeSieB alloys are known for their ability to form glass and * Corresponding author. E-mail address: kziewiec@up.krakow.pl (K. Ziewiec). Contents lists available at ScienceDirect Intermetallics journal homepage: www.elsevier.com/locate/intermet http://dx.doi.org/10.1016/j.intermet.2015.10.010 0966-9795/© 2015 Elsevier Ltd. All rights reserved. Intermetallics 69 (2016) 47e53