Densification kinetics of Mo-Ni-Sn composites in liquid-phase sintering

Abstract

The paper examines the densification kinetics in liquid-phase sintering of Mo-Ni-Sn samples containing 90 wt.% of molybdenum and 10 wt.% of liquid phase in which the content of nickel varies from 5 to 67.5 wt.%. The samples continuously densify with increasing nickel content. It is examined how the amount of the 28 wt.% Ni-72 wt.% Sn liquid phase influences the densification kinetics of samples with varying content of molybdenum. The densification parameter increases with the amount of the liquid phase.Liquid-phase sintering of multicomponent disperse systems whose components interact is a process that has been examined inadequately. The papers [1-5] analyze the densification mechanism in sintering of ternary pseudoalloys in which tungsten is a refractory component. A number of features in liquid-phase sintering resulting from the interaction between the refractory compounds and liquid phase and the interaction between the liquidphase components have been found in the W-Ni-Sn, W-Co-Sn, and W-Fe-Sn systems. Of interest is to examine these features when tungsten is replaced by molybdenum.This paper examines the densification kinetics of Mo-Ni-Sn pseudoalloys in liquid-phase sintering.We have found no data on the ternary Mo-Ni-Sn phase diagram. The Mo-Ni system has three incongruently melting intermediate phases, a wide region of solubility of molybdenum in solid nickel, and a very narrow region of nickel solid solutions in molybdenum [6]. In contrast to W-Ni, none of the Mo-Ni intermediate phases (namely, MoNi) decomposes at 1362°C, which raises the temperature of isothermal holding in sintering.The Mo-Sn phase diagram has not been finally established. Intermetallic MoSn 2 that decomposes at 800 ± 100°C and intermetallic Mo 3 Sn that decomposes at 300 ± 100°C are surely known to exist. There is one intermediate phase between these intermetallics which decomposes at 1200 ± 100°C but its composition has not yet been established (either Mo 2 Sn 3 or Mo 3 Sn 2 ) [6].The densification kinetics was examined with dilatometry. The displacement of the connecting rod resulting from shrinkage of the sample is converted by an inductive pickup into an electric signal proportional to the displacement [7]. The error of measurement is 2%.