Al Al3Ni Research Articles

Unidirectional solidification of ternary eutectic Al-Ni-Si alloys

Two monovariant alloys — type I (Al/6%Ni/0–2.5%Si) and type II (Al/12%Si/0–1.5%Ni) — and the ternary (Al-Ni-Si) eutectic have been studied. For the type I alloys particular attention was given to the effect of silicon concentration on the microstructural stability of the binary eutectic Al-Al 3Ni. Three distinct morphologies were observed, according to the solidification parameters. These were: well-aligned; aligned/cellular transitional; and cellular. The morphology of the silicon phase in the type II alloys was found to be very sensitive to any change in the solidification rate. The presence of very small amounts of nickel resulted in the formation of Al 3Ni; its growth was influenced by the kinetics and growth of the silicon phase. In the ternary eutectic, two of the three phases — Al 3Ni and Si — developed rod-like morphologies at the lowest solidification rates, with almost planar solid/liquid interfaces. As in the type II alloys, the silicon phase was sensitive to the solidification rate and it affected the growth of the Al 3Ni.

The tensile deformation of unidirectionally-solidified Al-Al 3Ni and Al-Al 2Cu : Cantor, B. and Chadwick, G. A. Journal of Materials Science, Vol 10 No 4 (April 1975) pp 578–588

The tensile deformation of unidirectionally-solidified Al-Al 3Ni and Al-Al 2Cu : Cantor, B. and Chadwick, G. A. Journal of Materials Science, Vol 10 No 4 (April 1975) pp 578–588

Crystallography of Al-Al 3Ni, Al-Al 2Cu and Al-ζ(AlAg) eutectics during nucleation and the early stages of growth

X-ray texture diffractometry has been used to investigate the crystallography of Al-Al 3Ni, Al-Al 2Cu and Al-ζ(AlAg) eutectics during nucleation and the early stages of growth. In each of the three eutectics, rapid nucleation is found to produce a dendritic morphology. There is no characteristic nucleation crystallography in Al-Al 3Ni or Al-Al 2Cu but nucleation of Al-ζ(AlAg) is epitaxial. Because of rapid competitive grain growth and crystallographic rotation, Al-Al 2Cu can establish a preferred growth crystallography. Grain growth and crystallographic rotation are more limited in Al-Al 3Ni and Al-ζ(AlAg), and the nucleation crystallography persists during growth.

Size effect in low temperature electrical resistivity of Al-Al 3Ni in situ composites : Simoneau, R. and Bégin, G. J App Physics, Vol 45, No 9 (Sept 1974) p 3828

Size effect in low temperature electrical resistivity of Al-Al 3Ni in situ composites : Simoneau, R. and Bégin, G. J App Physics, Vol 45, No 9 (Sept 1974) p 3828

The mechanical properties of directionally solidified aluminum-based eutectic castings

AbstractThe mechanical properties for directionally solidified Al-Al3Ni, Al-Si, and Al-Al2Cu eutectic castings have been determined and it is shown that the properties of castings (solidified at approximately 80 cm/hour) compare favourably to those obtained for slowly solidified eutectics (solidified at approximately 2 cm/hour). The strengths of Al-Al2Cu and Al-Si eutectic castings are higher than those obtained for slowly solidified alloys while the strengths for the Al-Al 3Ni eutectic castings are somewhat lower than for the slowly solidified alloys. The Al-Al3Ni and Al-Al2Cu cast eutectics essentially maintain their yield strength up to 300°C whereas the yield strength of the Al-Si eutectic decreases continuously with increasing temperature. It is concluded that the high strengths reported result from a combination of the fine micro-structure obtained from the relatively rapid solidification rate and by strengthening of the intermetallic phase. Reesume Les auteurs ont determine les proprietes mecanique...

Size effect in low-temperature electrical resistivity of Al–Al3Ni in situ composites

Fiber composites have been grown in situ by unidirectional solidification of Al–Al3Ni eutectic. The interfiber distance has been changed by more than an order of magnitude through variation of the solidification rate. The electrical resistivity, measured in directions perpendicular and parallel to the Al3Ni fiber axis, exhibited an important anisotropy and a marked dependence on the interfiber distance at 77 and 4.2 K. These experimental results are explained in term of partial specularity of reflections of conduction electrons on internal Al–Al3Ni interfaces.

The growth crystallography of unidirectionally solidified Al-Al 3Ni and Al-Al 2Cu eutectics

The steady-state growth crystallography of Al-Al 3Ni and Al-Al 2Cu eutectic single crystals has been determined using precise Kikuchi line electron diffraction techniques. Growth of Al-Al 3Ni is found to be controlled by anisotropic growth kinetics of the Al 3Ni phase, and there is a strong tendency for [010] Al 3Ni , the fibre axis and the growth direction to be mutually parallel. Subsidiary growth anisotropies prevent the aluminium phase orientation from being completely random. Orientation variations within individual crystals are very small. Growth of Al-Al 2Cu is found to be controlled by the formation of a low-energy solid-solid interphase boundary parallel to {111} Al and {211} Al 2Cu . However the crystallography can vary within individual crystals by as much as 8–10°.

Partitioning of stress between fiber and matrix during tensile deformation of the Al-Al 3Ni eutectic composite : Baromeo, C. and Courtney, T. H. Metallurgical Transactions, vol 4, no 8 (Aug 1973) pp 1821–1828

Partitioning of stress between fiber and matrix during tensile deformation of the Al-Al 3Ni eutectic composite : Baromeo, C. and Courtney, T. H. Metallurgical Transactions, vol 4, no 8 (Aug 1973) pp 1821–1828

Halo formation during unidirectional solidification of off-eutectic binary alloys

Halos of the non-faceted aluminum-rich phase have been observed around primary intermetallic dendrites in unidirectionally solidified Al-Al 3Ni and Al-Al 9Co 2 hypereutectic alloys, but no halos were observed in hypoeutectic alloys. Details of the influence of the growth rate on the halo fractions and morphologies have been determined. The model for halo formation from previous nucleation experiments is not satisfactory for the unidirectional growth experiments. A new model is proposed which shows the influence of details of the relevant phase diagram, as well as allowing for the effects of growth rate on the growth undercoolings of the two individual phases and of the coupled growth.

Low-temperature resistivity of two-phase Al–Al3Ni alloys

The electrical resistivity of Al–Ni alloys in the composition range 2–28 wt% Ni was investigated. The eddy-current decay method was used and the measurements were made at three temperatures: 297, 77, and 4.2 K. The results are explained in term of a series and parallel resistor model which takes into account the existence of different regions in the alloy (i.e., the continuous eutectic mixture, and the dispersed proeutectic constituents). This model permitted the resistivity curve to be fitted at the three temperatures and resistivity value for Al3Ni to be computed. The sharp maximum of resistivity at the eutectic composition, appearing at low temperature, has been attributed to the scattering of electrons on precipitate boundaries and to peculiar morphological features.

Microstructural characteristics of the directionally-solidified Al-Al 3Ni eutectic and their influence on creep fracture : Breinan, E. M., Thompson, E. R., McCarthy, G. P. and Herman, W. J. Metallurgical Transactions, Vol 3, No 1, p 221 (January 1972)

Microstructural characteristics of the directionally-solidified Al-Al 3Ni eutectic and their influence on creep fracture : Breinan, E. M., Thompson, E. R., McCarthy, G. P. and Herman, W. J. Metallurgical Transactions, Vol 3, No 1, p 221 (January 1972)

Creep behaviour of Al-Al 3Ni eutectic composites : Breinan, E. M., Thompson, E. R. and Tice, W. K. Metallurgical Transactions, Vol 3, No 1, p 211 (January 1972)

Creep behaviour of Al-Al 3Ni eutectic composites : Breinan, E. M., Thompson, E. R. and Tice, W. K. Metallurgical Transactions, Vol 3, No 1, p 211 (January 1972)

Fiberless region defects in unidirectionally-solidified Al-Al 3Ni eutectic : Gangloff, R. P., Kraft, R. W. and Wood, J. D. Metallurgical Transactions, Vol 3, No 1, p 348 (January 1972)

Fiberless region defects in unidirectionally-solidified Al-Al 3Ni eutectic : Gangloff, R. P., Kraft, R. W. and Wood, J. D. Metallurgical Transactions, Vol 3, No 1, p 348 (January 1972)

Mechanical behaviour of rapidly solidified Al-Al 2Cu and Al-Al 3Ni composites : Lawson, W. H. S. and Kerr, H. W. Metallurgical Transactions, Vol 2, No 10, pp 2853–2859 (October 1971)

Mechanical behaviour of rapidly solidified Al-Al 2Cu and Al-Al 3Ni composites : Lawson, W. H. S. and Kerr, H. W. Metallurgical Transactions, Vol 2, No 10, pp 2853–2859 (October 1971)

Cellular morphologies in rapidly solidified Al-Al 2Cu and Al-Al 3Ni eutectic alloys

The cellular structures found in impure specimens of Al-Al 2Cu and Al-Al 3Ni eutectic alloys solidified at 0.44 to 2.88 mm/sec have been investigated. In Al-Al 2Cu elongated cells containing parallel traces of mismatch surfaces were found at the lowest solidification rate, but the traces were arranged more randomly and the cells became more equiaxed as the rate of solidification increased. In Al-Al 3Ni the cells displayed a specific shape within each eutectic grain at the lowest solidification rate, but were less crystallographic in nature at the faster rates. The crystallographic orientation relation between eutectic phases has been determined for both eutectics and compared with data for the same systems solidified more slowly.

Elevated temperature stability of the Al-Al 3Ni eutectic composite : Smartt, H. B., Tu, L. K. and Courtney, T. H. Metallurgical Transactions, Vol 2, No 9, pp 2717–2727 (September 1971)

Elevated temperature stability of the Al-Al 3Ni eutectic composite : Smartt, H. B., Tu, L. K. and Courtney, T. H. Metallurgical Transactions, Vol 2, No 9, pp 2717–2727 (September 1971)

High-speed solidification of several eutectic alloys

Samples of Ag-Cu, Zn-Al, Al-CuAl 2, Al-Al 3Ni and Mg-γ(MgAl) eutectic alloys have been directionally solidified at speeds up to 2 × 10 −1 cm/sec. The resulting microstructures were analyzed by electron microscopy to determine the dependence of interphase spacing λ on growth rate v. Data are consistent with the relation λαμ −1 2 predicted by theory. A simplified thermal analysis is used to estimate the maximum attainable rate of directional solidification.

The freezing of some continuous binary eutectic mixtures

Abstract Directional freezing experiments have been carried out with the binary eutectic mixtures, Al–Ag2Al, Al–CuAl2, Al–Zn, Al–Al3Ni, Ag–Cu, LiF–NaF and NaF–NaCl. Various aspects of eutectic solidification are discussed with particular reference to the importance of solid interfacial energy. The work is divided into three parts. I. A description of the observed microstructures, with discussion of the type of dispersion occurring in unmodified eutectics and the modification of lamellar arrangements by impurity cell formation. II. An account of the development of preferred orientations during the directional freezing of some eutectics. III. Measurements of the interphase separations as functions of the freezing rates and a discussion of the influence of solid interfacial energy upon these.