Mechanical behavior of rare-earth orthophosphates near the monazite/xenotime boundary characterized by nanoindentation

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:691

Article

Wilkinson, Taylor M.¹  Wu, Dong¹  Musselman, Matthew A.¹  Li, Nan²  Mara, Nathan^2,3  Packard, Corinne E.¹ 

[1] Colorado Sch Mines, Met & Mat Engn Dept, Golden, CO 80401 USA

[2] Los Alamos Natl Lab, Ctr Integrated Nanotechnol, Los Alamos, NM 87545 USA

[3] Los Alamos Natl Lab, Inst Mat Sci, Los Alamos, NM 87545 USA

关键词: Nanoindentation;    Mechanical characterization;    Ceramics;    Phase transformation;    Twinning;   

DOI  :  10.1016/j.msea.2017.03.041

来源: Elsevier

【 摘 要 】

Low elastic modulus and hardness, as well as anomalous indentation behavior, have been observed during indentation of xenotime rare-earth orthophosphate ceramics (REPO(4)s) with compositions near the monazite/xenotime phase boundary. Pressure-induced phase transformation has been identified as a potential cause for both observations. This study comprehensively characterizes the mechanical properties and indentation behavior of four elemental REPO4 materials (EuPO4, GdPO4, TbPO4, and DyPO4) that span the monazite/xenotime phase boundary using ex situ nanoindentation for a range of loading rates and indentation depths. In situ nanoindentation within a SEM was used to correlate discrete load-depth behavior to the development of surface features. Anomalous, elbow-type behavior was not restricted to xenotimes, but occurred in all four materials; thus we concluded that the presence of an elbow in the indentation data was not a unique identifier of phase transformation in rare-earth orthophosphates. Furthermore, it was shown that the elastic modulus of each of these compositions approached the value predicted by simulations and hardness was consistently above 5 GPa, provided that the samples were processed to nearly full density.

【 授权许可】

Free