Structural evolution of spark plasma sintered AlFeCuCrMgx (x = 0, 0.5, 1, 1.7) high entropy alloys. (October 2016)

• Record Type: Journal Article
• Authors: Maulik, Ornov; Kumar, Devesh; Kumar, Saurav; Fabijanic, Daniel M.; Kumar, Vinod
• Is Part Of: Intermetallics. Volume 77(2016:Oct.)
• Page Start: 46
• Page End: 56
• Publication Date: 2016-10
• Subjects: High entropy alloy -- Spark plasma sintering -- Transmission electron microscopy (TEM) -- Phase transformation -- Diffraction; Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2016.07.001
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract: The present paper reports synthesis of novel AlFeCuCrMgx (x = 0, 0.5, 1, 1.7 mol) high entropy alloys (HEAs) by mechanical alloying (MA) followed by spark plasma sintering (SPS). Phase evolution, microstructure and phase transformation study of the sintered alloy were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). XRD of the sintered alloys revealed the formation of two BCC phases in the AlFeCuCr alloy and more complex structures in AlFeCuCrMgx (x = 0.5, 1, 1.7) alloys containing AlFe type, BCC, and Cu2 Mg type phases. TEM bright field image and selected area diffraction pattern (SAED) revealed the formation of tetragonal closed packed Cr precipitates within the Cu2 Mg phase of AlFeCuCrMgx alloys (x = 0.5, 1, 1.7). DSC study of the alloys revealed no substantial phase change up to 1000 °C for AlFeCuCr alloy. Although, for x = 0.5, 1 & 1.7 phase transformation occurs at 818 °C, 885 °C & 483 °C respectively. Mg content had a significant effect on hardness, increasing to a peak hardness of 853 HVN for AlFeCuCrMg0.5 alloy before decreasing to 533 HVN for the AlFeCuCrMg1.7 alloy. The phase evolution in these alloys has been considered using thermodynamic parameters, and the structure-property relationship has also been proposed by conventional strengthening mechanisms. Graphical abstract: Highlights: Mechanically alloyed AlFeCuCrMgx (x = 0, 0.5, 1, 1.7) HEA were successfully spark plasma sintered. Phase evolution after sintering was characterized by XRD, SEM and TEM. Microstructure of the HEAs suggests a formation of multi-phase system. Thermodynamical parameters were conferred to understand the formation of phases. Structure-property correlation has been studied in detail.