MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
ISSN-L : 1345-9678
Effects of Injection Velocity on Distribution of Primary α-Phase Particles in Semi-Solid High Pressure Die Casting of JIS AC4CH Aluminum Alloy
Yuichiro MurakamiKenji MiwaMasayuki KitoTakashi HondaNaoyuki KanetakeShuji Tada
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2015 Volume 56 Issue 2 Pages 206-211

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Abstract

We have previously developed a new injection process with improved fluidity through applying shear stress. In this process, the product is made by injecting a solid-liquid slurry. Therefore, the microstructure of products made by this semi-solid injection process shows the dispersal of the spherical primary α-phase particles in the matrix. The primary α-phase particles and matrix are formed from the solid phase and liquid phase, respectively, when the slurry is injected. These phases have different properties, and the properties of semi-solid products are thought depend on the distribution of the primary α-phase particles. For this reason, semi-solid products have characteristic microstructures.
In the present study, the distribution of primary α-phase particles was investigated in fluidity test specimens made of JIS AC4CH aluminum alloy, formed in a spiral cavity at various injection speeds. The number of primary α-phase particles at the edge of the specimens was higher than for other observation points. The primary α-phase particles were distributed homogeneously on the plane perpendicular to the flow direction at the edge of the specimens. In specimens formed at high injection speeds, at the observation points from the gate to the middle of the flow length, the primary α-phase particles were concentrated at the central axis of the flow direction. However, in specimens formed at low injection speeds, the primary α-phase particles were also distributed homogeneously in these areas. The concentration of the primary α-phase particles around the central axis was affected by the flow velocity in the cavity. These results suggest that the distribution of the primary α-phase can be controlled by changing the flow velocity.

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© 2014 Japan Foundry Engineering Society
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