Microstructure and tensile properties of high-strength high-ductility Ti-based amorphous matrix composites containing ductile dendrites

• Published in: Acta materialia Vol. 59; no. 19; pp. 7277 - 7286
• Main Authors: Oh, Yoon S., Kim, Choongnyun Paul, Lee, Sunghak, Kim, Nack J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-11-2011; Elsevier
• Subjects: Amorphous matrix composite; Applied sciences; Bands; Deformation mechanisms; Dendrite; Dendritic structure; Elongation; Exact sciences and technology; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Necking; Strain hardening; Strain-induced phase transformation; Tensile properties; Titanium; Twin; Strain hardening; Amorphous matrix composite; Dendrite; Twin; Strain-induced phase transformation; Ductility; Mechanical properties; Tensile property; Composite material; Tensile strength; Phase transformation; Microstructure; Strength
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2011.08.006

In the present study, two Ti-based amorphous matrix composites containing ductile dendrites dispersed in an amorphous matrix were fabricated by a vacuum arc melting method, and deformation mechanisms related to the improvement of strength and ductility were investigated by focusing on how ductile dendrites affected the initiation and propagation of deformation bands, shear bands or twins. Ti-based amorphous matrix composites contained 70–73vol.% coarse dendrites of size 90–180μm, and had excellent tensile properties of the yield strength (1.2–1.3GPa) and elongation (8–9%). The Ta-containing composite showed strain hardening after yielding, and reached fracture without showing necking, whereas necking occurred straight after yielding without strain hardening in the Nb-containing composite. The improved tensile elongation and strain hardening behavior was explained by the homogeneous distribution of dendrites large enough to form deformation bands or twins, the role of β phases surrounding α phases to prevent the formation of twins, and deformation mechanisms such as strain-induced β to α transformation.