ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
A tungsten heavy alloy (92%W, Ni-Co matrix) is subjected to severe plastic deformation(SPD) by high pressure torsion (HPT) at room temperature up to equivalent strains of 0.7, 5.3, 10.7and 14.3. The microstructure and the mechanical properties are investigated by cylindricalcompression samples at quasi-static and dynamic loading. The harder spherical W particles arehomogeneously deformed within the softer matrix, becoming ellipsoidal at medium strains andbanded at high strains without shear localization or fracture. Results of quasi-static loading showthat the strength is approaching a limiting value at strains of ~10. At this strain for the matrix a grainsize of ~80 nm and for W a cell size of ~250 nm was observed, suggesting strain concentration onthe matrix. The initial yield stress of 945 MPa for the coarse-grained condition is increased therebyto an ultimate value of 3500 MPa, while a peak stress of ~3600 MPa is reached. Such remarkablystrength has never been reported before for pure W or W-based composites. The strain hardeningcapacity as well as the strain rate sensitivity is reduced drastically, promoting the early formation of(adiabatic) shear bands
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/19/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.584-586.405.pdf
