Aluminium alloys play a key role in modern engineering since they are the most used non-ferrous material. They have been widely used in automotive, aerospace, and construction engineering due to their good corrosion resistance, superior mechanical properties along with good machinability, weldability, and relatively low cost. The progress in practical application has been determined by intensive research and development works on the Al alloys. A new class of Al–REM–TM aluminum alloys (REM indicates rare earth metal and TM is transition metal) was revealed in the end of the last century. These alloys differ from conventional ones by their extraordinary ability to form metal glasses and nanoscale composites in a wide range of compositions. Having low density, these alloys possess unique mechanical characteristics and corrosion resistance. Two as received alloys, namely Al₈₅Ni₉Fe₂La₄ and Al₈₅Ni₇Fe₄La₄ were obtained in the form of ingots from melts of corresponding compositions upon cooling in air were studied by scanning/transmission electron microscopy (STEM), energy dispersive X-ray (EDX) microanalysis and X-ray diffraction (XRD). The microstructural analyses were performed in a aberration corrected TITAN 80-300 TEM/STEM (FEI, USA) attached with EDX spectrometer with ultrathin window (EDAX, USA). The specimens for transmission electron microscopy (TEM) were prepared by an electrochemical or ion etching. It was found that the received alloys exhibits along with fcc Al and Al4La (Al11La3) particles, these alloys contain a ternary phase Al3Ni1 ⎯ хFeх isostructural to the Al3Ni phase and a quaternary phase Al8Fe2 ⎯ хNiхLa isostructural to the Al8Fe2Eu phase and monoclinic phase Al₉(Fe,Ni)₂ isostructural to the Al₉Co₂. The study by HRSTEM together with a new atomic resolution energy dispersive X-ray microanalysis method demonstrated that Fe and Ni atoms substituted one another in the Al8Fe2-хNiхLa quaternary compound. Besides, several types of defects were determined: first ones have a form of a δ -layers and they are Al3.2Fe1-хNix ternary compound with a Al3.2Fe structure type. Second ones were point defects, which are La vacancies.

The experimental part of this work was partially done on the equipment of the Resource Center of Probe and Electron Microscopy (Kurchatov Complex of NBICS- Technologies, NRC “Kurchatov Institute”)

Figures:

Fig. 1. Secondary electron SEM image of the Al85Ni7Fe4La4 alloy surface: (1) Al, (2) Al3Ni1 ⎯ xFex, (3) Al4La (Al11La3), and (4) Al8Fe2 ⎯ xNixLa

Fig. 2. TEM image of Al9(Fe,Ni)2 particle in B [111] zone axis.

Fig. 3. The HAADF image of Al8Fe2-xNixLa particle in B [101] zone axis and atomic resolution Fe and Ni maps.

Fig. 4. The atomic resolution Fe and La maps are in the inserts.

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EMC Abstracts - https://emc-proceedings.com/abstract/study-the-microstructure-of-three-and-four-component-phases-in-al-ni-fe-la-alloys/