Solid Solubility in Cu5Gd1−xCax System: Structure, Stability, and Hydrogenation. (13th March 2017)

• Record Type: Journal Article
• Authors: Kocjan, Andraž; Kelhar, Luka; Gradišek, Anton; Likozar, Blaž; Žagar, Kristina; Ghanbaja, Jaafar; Kobe, Spomenka; Dubois, Jean-Marie
• Other Names: Lejcek Pavel Academic Editor.
• Is Part Of: Advances in materials science and engineering. Volume 2017(2017)
• Publication Date: 2017-03-13
• Subjects: Materials science -- Periodicals; Materials science; Periodicals; 620.11
• DOI: 10.1155/2017/9203623
• Languages: English
• ISSNs: 1687-8434

Abstract

Abstract : We report on synthesis and characterization of a novel group of compounds based on copper, gadolinium, and calcium. Cu-Ca and Cu-Gd binaries were previously studied while Ca and Gd are known to be immiscible themselves. The effects of substituting Gd with Ca in Cu5 G d 1 - x C a x compounds (0 ≤ x ≤ 1 ) were studied by investigating the phase stability and crystal structure of the resulting new compounds in five specimens with x = 0, 0.33, 0.50, 0.66, and 1, respectively. The samples produced by melt-spinning had hexagonal P6/mmm structure, irrespective of Ca amount (x ), where lattice parameters varied with x linearly. This is an indication of good solid solubility under the preparation conditions. A slower cooling upon arc-melting caused the liquid phase separation into Cu4.5 Gd and Cu-Ca compounds. Using TEM, rapidly solidified ribbons (Cu5 Gd0.5 Ca0.5 ) were investigated and the formation of a homogeneous ternary phase with a nearly nominal stoichiometric composition and minor amounts of Cu-Ca secondary phase was observed. Using DSC and HT XRD, we found that these systems are stable at least up to 400°C. Upon a 16-hour hydrogenation at 1 bar and 300°C, all specimens absorbed about 0.5 wt.% of hydrogen. This caused changes in structure with the formation of pure Cu and H2 G d 1 - x C a x solid solution.