Papers by Keyword: Triboalloys

Abstract: Severe plastic deformation processes are used to refine grain structure by means of very high deformations. Equivalent Von-Mises strains in the range of 5.06 to 11.57 were obtained using the accumulative roll-bonding (ARB) process. The effect of the initial microstructure is analyzed. Microstructure, microhardness and tensile strength of the alloy, both starting with previously cold-rolled material and after a 30 minute, 300 °C heat treatment, are compared. The effect of a heat treatment after 5 steps of ARB ( = 8.11) is also presented. Results show that even though both the microhardness and tensile strength go up with increasing deformation, they are not related to each other by a factor of 3. The highest values of these parameters depend more on the initial microstructure than on the total deformation. A better distribution of the second phase and an increase in solid solubility are also observed after ARB.

Abstract: A 95% cold-rolled Al-20%Sn-1%Cu alloy was heat-treated in a range of temperatures and times to investigate the evolution of mechanical properties and microstructure. The most interesting combination of properties can be achieved between 300 and 400°C in a process that is simpler than what is used in industry. The physical phenomena which are active during the heat treatment are precipitation, recovery, recrystallisation and change in phase distribution due to surface tension. The former two predominate at low temperatures, while the latter achieve faster kinetics at higher temperatures, where recrystallisation is coupled to the change in morphology of the contiguous Sn-phase.

Abstract: Rapidly solidified industrially stripcast Pb-Sb-Sn triboalloys showed microstructures typical for the eutectic decomposition of metallic glasses. Evidence was found of crystallisation above the glass transition temperature and ageing at room temperature. The observation supports a previous hypothesis by the authors on the wear properties of soft tribological alloys.