Abstract
Babbitt alloys are traditionally used as a material for sliding bearings of large-sized units. The structure of babbit Sn11Sb5,5Cu consists of three phases: alpha-phase, which is a solid solution of antimony and copper in the tin, beta-phase is a SnSb crystal with hexagonal and rhombohedral lattice and small eta-phase (Cu6Sn5). Refinement of large intermetallic particles in babbitts structure leads to increase of the service life of the sliding bearing.
The paper studied the influence of severe plastic deformation by high pressure torsion on the microstructure and microhardness of cast babbit Sn11Sb5,5Cu.
Cast babbitt Sn11Sb5, 5Cu is characterized by a microstructure with large cubic beta-phase particles SnSb with a size of 100-200 mkm, small eta-phase in the form of large needles Cu6Sn5. The bulk alpha-phase is submicrocrystalline with grain size of 1-3 mkm.
The billets were subjected to high pressure torsion on Bridgman anvils at room temperature for 2, 5 and 10 turns, which corresponded to a true logarithmic degree of deformation 7, 8 and 9.
After high pressure torsion with e = 7, the refinement and spheroidizing of beta-phase from an initial size to the 15-20 microns occur, a further increasing of the degree of deformation does not lead to a change in beta-phase size. In the beta-phase grain refinement occurs. At e =7 and 8 grain size consist 1 mkm, when e = 9 grain size was about 200 nm.
Microhardness measurements revealed that high pressure torsion with e = 9 increased the microhardness of babbit Sn11Sb5,5Cu by 80%.
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