Texture development and deformation mechanisms during uniaxial straining of U-Nb shape-memory alloys

• Published in: Philosophical magazine (Abingdon, England) Vol. 85; no. 13; pp. 1441 - 1457
• Main Authors: Field, R. D., Brown, D. W., Thoma, D. J.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis Group 01-05-2005; Taylor and Francis
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deformation and plasticity (including yield, ductility, and superplasticity); Exact sciences and technology; Martensitic transformations; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Inorganic compounds; Deformation; Tetragonal lattices; Phase transformations; Neutron diffraction; Metastable states; Niobium alloys; Actinide alloys; Twinning; Experimental study; Monoclinic lattices; Texture; Shape memory effects; Binary alloys; Phase boundaries; Uranium alloys; Stress effects; Transition element alloys
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786430500036314

The shape-memory effect is well documented in uranium-niobium alloys near the α″-γ
o
metastable phase boundary. In situ neutron diffraction measurements during uniaxial loading indicate that U-14 at.% Nb (in the α″ monoclinic phase field) deforms by stress-induced twin reorientation. Alternatively, U-16 at.% Nb (initially γ
o
tetragonal) undergoes a stress-induced phase transformation to the α″ monoclinic phase. The crystallographic texture of the monoclinic phase of both compositions has been measured and qualitatively interpreted by considering the orientation relationship between the most favoured α′′ variant and the parent phase. In addition, previously published observations of deformation structures within the shape-memory regime of a U-13 at.% Nb alloy are discussed within the context of the same model.