Pure Al Melt Research Articles

Interaction of steel with pure Al, Al–7Si and A356 alloys

Carbon steel bars were dipped in aluminum alloy melts for different periods of time. A reactive iron–aluminum intermetallic layer grew at the interface between the melt and the steel substrate. This reactive layer was mainly composed of intermetallic Fe–Al (Fe 2Al 5) and its thickness was influenced by dipping time (3–60 min), surface roughness (0.74 μm versus 0.07 μm) and carbon content (0.2–0.4 wt%) of the steel bars and the elements (mainly Si and Mg) added in the aluminum alloys. An oxide film, which existed at the interface between steel bar and melt, hampered the Al–Fe reaction. In comparison with a pure Al melt, the thickness of the reactive layer of the Al–7Si alloy melt decreased after a very short dipping time (3 min), increased following an increase in the dipping time (10 min) then decreased after a long dipping time (>20 min). The thickness of the reactive layer of a 1040 steel bar dipped in an A356 alloy (Al–7Si–0.4Mg) melt for a given dipping time at 973 K, was the narrowest among all melts studied; including pure Al, Al–7Si, Al–1Mg and Al–7Si–0.4Mg alloys.

A new technique to refine pure aluminum by Al–Ti–C mold

A new technique to refine commercially pure aluminum was presented, in which the pure Al melt was cast into an Al–Ti–C mold after flowing through an Al–Ti–C launder in the presence of electromagnetic field, and the refinement effect was also investigated. The experimental results indicate that the chill surface of the ingots can be more effectively refined by Al–5Ti–0.4C mold than by Al–7Si mold. In the presence of electromagnetic field, the forced convection significantly modifies the flow pattern and temperature field, which leads to a substantial amelioration of the surface quality and a marked reduction of the grain size. A uniform and fine equiaxed as-cast structure was obtained when the melt flows through an Al–5Ti–0.4C launder before casting into the Al–5Ti–0.4C mold with electromagnetic vibration, and the main reason for this is that the launder wall and the mold wall become permanent and continuous nucleation substrates from which α-Al grains come forth and depart because of the presence of substantial TiC particles and electromagnetic vibration.

Preparation of Al-Al2O3 in-situ particle composites by addition of Fe2O3 particles to pure Al melt

Preparation of Al-Al2O3 in-situ particle composites by addition of Fe2O3 particles to pure Al melt

Thermal conductivities of hypoeutectic Al-Cu alloys during solidification and cooling

The thermal conductivity of hypoeutectic Al-Cu alloys during solidification and cooling was estimated by combining available data on electrical resistivity and thermal conductivity. To estimate the thermal conductivity of the solid alloys, the Smith-Palmer equation was used. This equation enables one to closely estimate the thermal conductivities from known data on electrical conductivities. The electrical resistivities of Al-Cu melts were also gathered. The Smith-Palmer equation was tested successfully for pure Al-melt and assumed to apply to Al-Cu melts, so that their thermal conductivities could be estimated. Finally simple-mixture models were applied to estimate the electrical resistivities and thermal conductivities of the alloys during solidification.

Al-Al 2O 3 in situ particle composites by reaction of CuO particles in molten pure Al

CuO particles were incorporated into pure Al melt to produce Al-Al 2O 3 in situ particle composites. α-Al 2O 3 and Cu particles were identified in the particles extracted from the composites. Part of the reduced Cu dissolved in the matrix of the composites and increased its microhardness. The hardness and tensile strength of the composites were improved significantly as compared to those of pure Al.

無加圧浸透現象を利用した金属間化合物複合材料の作製と圧縮特性

The titanium aluminide intermetallic matrix composites are synthesized by the spontaneous infiltration of a raw powder phase containing Ti powder with molten pure Al. This paper deals with (i) the effect of adding Al2O3 and Al to Ti powder on the spontaneous infiltration and (ii) the result of the compressive test. In the case of using only Ti powder as a raw powder phase, the crucible is destroyed by the rapid increase in temperature due to the exothermic reaction between Ti powder and pure Al melt. However, it was found that the addition of Al2O3 particles to Ti powder allows the spontaneous infiltration without the crucible fracture. Excess additions of Al2O3 particles prevent the spontaneous infiltration of the mixed powder with molten pure Al. This is because the excess amount of Al2O3 particles acts as an obstacle between Ti and Al, and as a result, molten pure Al cannot contact with Ti powder effectively. The result of the XRD analysis suggests the formation of Al3Ti by spontaneous infiltration. In the case of adding pure Al powder to the raw powder phase, molten pure Al can infiltrate without the addition of Al2O3 particles, and the infiltration occurs more thoroughly and the microstructure becomes more homogeneous. The compressive strength of the Al2O3 dispersed Al3Ti is 592 MPa, which is 100 MPa higher than that of the Al3Ti made by this infiltration process.