Design of quasicrystal alloys with favorable tribological performance in view of microstructure and mechanical properties

Abstract

Quasicrystals have been used in various applications to improve wear resistance as well as friction. It is known that quasicrystal (i-phase) content and microstructure in alloys have a decisive effect on the mechanical properties and tribological performance. In this research, four (beta + i)-dual-phased quasicrystal alloys with different i-phase content and grain size were developed to alleviate the brittleness of the i-phase with the help of the soft beta-phase. The influences of the i-phase content and grain size were investigated through impact test, wear test, and analysis. Through the annealing process, the amount of the i-phase was increased by about 38% (59.24% -> 81.75%), and, besides, the grain size of the i-phase was simultaneously increased from 3.47 mu m up to 9.98 mu m. As the amount of i-phase increased, it was possible to increase the hardness from 712 HV to 763 HV. Meanwhile, the increased grain size (i-phase) reduced the contact stress of the grain during wear testing: thus, the specific wear rate could be decreased from 2.21 x 10(-4) mm(3)/Nm to 0.5 x 10(-4) mm(3)/Nm. Not only that, but an experimental wear equation was obtained using empirical data to predict the wear behavior of the dual-phased alloys. (C) 2020 Published by Elsevier Ltd.