Development and homogeneity of microstructure and texture in a lamellar AlCoCrFeNi 2.1 eutectic high-entropy alloy sever
- PDF / 1,485,097 Bytes
- 13 Pages / 584.957 x 782.986 pts Page_size
- 54 Downloads / 137 Views
FOCUS ISSUE
NANOCRYSTALLINE HIGH ENTROPY MATERIALS: PROCESSING CHALLENGES AND PROPERTIES
Development and homogeneity of microstructure and texture in a lamellar AlCoCrFeNi2.1 eutectic high-entropy alloy severely strained in the warm-deformation regime Seelam Rajasekhar Reddy1, Upender Sunkari1, Adrianna Lozinko2, Sheng Guo2, Pinaki Prasad Bhattacharjee1,a) 1
Department of Materials Science and Metallurgical Engineering, IIT Hyderabad, Telangana 502285, India Industrial and Materials Science, Chalmers University of Technology, Gothenburg 41296, Sweden a) Address all correspondence to this author. e-mail: [email protected] 2
Received: 18 July 2018; accepted: 10 October 2018
The effect of severe warm rolling on microstructure and texture homogeneities was investigated in a lamellar (L12 1 B2) AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA). The EHEA 90% warm-rolled at 400 °C showed disordering of the L12 phase and a remarkable increase in hardness. A much finer microstructure was observed on ND-RD (Normal Direction-Rolling Direction) plane as compared with that on the RD-TD (Rolling DirectionTransverse Direction) plane. The L12/Face Centered Cubic (FCC) phase developed a-fiber texture ND//〈110〉 with a particularly strong brass ({110}〈112〉) component, while the B2 phase developed the usual RD (//〈110〉) and ND (//〈111〉) fibers. Nevertheless, inhomogeneities in texture were noticed. Upon annealing at 800 °C, the ND-RD showed an ultrafine microduplex structure, while the RD-TD showed a retained lamellar structure. A rather uniform microduplex structure evolved after annealing at 1200 °C due to the accelerated kinetics of transformation at higher temperatures. The L12/FCC phase showed the retention of the a-fiber components, while the B2 phase showed stronger ND-fiber after annealing, although inhomogeneities in texture existed.
Introduction In a marked departure from the traditional alloy design strategy, which is based on one principal component to which other alloying elements are added in suitable proportions, high-entropy alloys (HEAs) have been proposed as novel multicomponent (usually greater than five) systems having the constituents in equiatomic or near-equiatomic concentrations [1]. In spite of the evident compositional complexities, the HEAs may yet show simple crystal structures, such as Face Centered Cubic (FCC) (e.g., equiatomic CoCrFeMnNi [2]), Body Centered Cubic (BCC), FCC 1 BCC [1], Hexagonal Close Packed (HCP) solid solution [3], or major HCP phase containing minor unindexed second phases [4], due to their high configurational entropy (DSconf) [1]. More recently, the definition of HEAs has been expanded to include non-equiatomic and multiphase alloys, so that the advent of HEAs has opened up the massive composition space to develop alloys with novel microstructure and mechanical properties [5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16].
ª Materials Research Society 2019
Eutectic high-entropy alloys (EHEAs) are a subclass of HEAs originally proposed as novel materials with high rupture strength and good cr
Data Loading...
