Review: liquid phase sintering

Abstract

Liquid phase sintering (LPS) is a process for forming high performance, multiple-phase components from powders. It involves sintering under conditions where solid grains coexist with a wetting liquid. Many variants of LPS are applied to a wide range of engineering materials. Example applications for this technology are found in automobile engine connecting rods and high-speed metal cutting inserts. Scientific advances in understanding LPS began in the 1950s. The resulting quantitative process models are now embedded in computer simulations to enable predictions of the sintered component dimensions, microstructure, and properties. However, there are remaining areas in need of research attention. This LPS review, based on over 2,500 publications, outlines what happens when mixed powders are heated to the LPS temperature, with a focus on the densification and microstructure evolution events.

Effect Of Compaction Pressure And Sintering Temperature On The Liquid Phase Sintering Behavior Of Al-Cu-Zn Alloy

“…However, when sintered at 560 • C, the density was significantly decreased for all compaction pressures, attributed to the expansion of volume. At this temperature, Al-Zn and Cu elements form small amount of liquid phase with Al, and the diffusion from the liquid to solid phase expands interparticle distance forming unfilled skeleton of the powder body, resulting in the increase of volume [14][15][16][17]. When sintered at 615 • C, in which LPS actively occurs in addition to solid state sintering, the density increases compared to that achieved at 560 • C because of the volume shrinkage by dissolution of solid into the liquid phase.…”

The Porosity Evaluation during ECAP in Aluminium PM Alloy

“…Previous investigations [12 17] show that sintering contributes to the formation of secondary porosity during transient liquid phase sintering (LPS) the swelling presented seems to be related to the amount of liquid generated (the deeper information about the LPS phenomenon is presented in review [18] and concerning aluminium PM alloys in [19,20]). The mix of primary, secondary and residual porosity is revealed by the mean values of pores size decreasing with increasing pressing pressure.…”

Advance on Al2O3Particulates Reinforced Aluminum Metal Matrix Composites (Al-MMCs) Manufactured by the Power Metallurgy(PM) Methods- Improved PM Techniques

“…Generally there was no solubility between the liquid and solid, so the densification occurred at the rate associated with sintering the solid skeleton and the liquid is simply a pore filling agent [39,40].The amount of the liquid phase had a significant impact on the sintering trajectory. It seemed that liquid phase infiltrate into space between ceramic agglomerate, the more liquid amount was required to obtain the enhanced sinterability of composite materials [38].…”

“…So there was no longer persistence of liquid phase during sintering. To achieve persistent liquid phase sintering, the solid and liquid contents should converge to constant values while the pores was annihilated, giving densification [39].…”