Microsegregation and solidification shrinkage were studied on copper-lead base alloys. A series of solidification experiments was performed, using differential thermal analysis (DTA) to evaluate the solidification process. The chemical compositions of the different phases were measured via energy dispersive X-ray spectroscopy (EDS) for the Cu-Sn-Pb and the Cu-Sn-Zn-Pb systems. The results were compared with the calculated data according to Scheil's equation. The volume change during solidification was measured for the Cu-Pb and the Cu-Sn-Pb systems using a dilatometer that was developed to investigate the melting and solidification processes. A shrinkage model was used to explain the volume change during solidification. The theoretical model agreed reasonably well with the experimental results. The deviation appears to depend on the formation of lattice defects during the solidification process and consequently on the condensation of those defects at the end of the solidification process. The formation of lattice defects was supported by quenching experiments, giving a larger fraction of solid than expected from the equilibrium calculation.

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The initial stage of liquid phase sintering, involving liquid reaction and particle growth, has been investigated under microgravity in experiments using tungsten heavy alloys for short periods of time (8-14 seconds). The influence of different factors, such as alloy composition, plastic deformation, and non-equilibrium conditions, have been evaluated. During the liquid phase sintering of tungsten heavy alloys at about 1470°C, the liquid matrix penetrates the tungsten particle agglomerates. A fraction of the tungsten particles goes into solution in the liquid phase and the original tungsten powder size will initially be reduced. At the same time, the agglomerates of tungsten particles are effectively separated. In a second stage, larger particles grow in equilibrium with the matrix while pure tungsten particles are dissolved into the matrix. When equilibrium is reached, the tungsten particles start to grow in the liquid Ni-Fe-W matrix phase in accordance with the Ostwald ripening pro-a c b d cess. A theoretical treatment of the particle solution a powder mixture; b liquid formation; c liquid penetration; and growth during these stages is proposed. d particle separation The addition of iron and cobalt to the W-Ni system 1 Illustration of initial stage of LPS showing liquid (dark) reduces the rate of penetration and growth. Non-equipenetration of particle agglomerates (white) and librium conditions during the formation of a liquid separation of particles phase have a marked effect on the tungsten particle separation. Milling of the tungsten powder increases the initial growth of tungsten particles. PM/0942 The aim of this work is to evaluate how parameters, The authors are at the Royal Institute of Technology, such as alloying elements, non-equilibrium conditions, Department of Production Engineering, Casting of milling of the tungsten powder, and deformation of the Metals, S-100 44 Stockholm, Sweden. Manuscript powder during compaction, influence the initial part of the

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Solidification shrinkage is an important concept in achieving sound castings. In the present work solidification shrinkage was studied in copper-lead and copper-lead-tin alloys. A series of solidification experiments was performed under different cooling rates using a dilatometer which was developed for melting and solidification purposes. The volume change was measured during primary solidification and the monotectic reaction. In order to explain the volume-changing results, the sample macrostructures were studied to evaluate gas and shrinkage cavities which were formed during the solidification. Furthermore, the volume fraction of the primary phase during solidification was evaluated in the samples that were quenched from different temperatures below the liquidus temperature. A shrinkage model was used to explain the volume changes during solidification.