Showing papers on "Directional solidification published in 1972"
01 Nov 1972-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, the authors applied the directional solidification technique to investigate the complicated solidification sequence in a commercial austenitic stainless steel which was known to yield a primary precipitation of § ferrite when cast into a 5 tons ingot.
Abstract: The directional solidification technique was applied in order to investigate the complicated solidification sequence in a commercial austenitic stainless steel which was known to yield a primary precipitation of § ferrite when cast into a 5 tons ingot. Three stages of solidification were found. The first precipitation of § ferrite was interrupted by precipitation of austenite and at the end of the solidification there was a transition back to precipitation of § ferrite. The competition between the first two stages is affected by the cooling rate and the nitrogen content. The precipitation of austenite from the melt results in the usual coring whereas o ferrite forms with a very homogeneous composition, presumably due to rapid diffusion in this phase. On cooling austenite forms from the § ferrite and this reaction also results in coring, presumably due to rapid diffusion in § ferrite.
100 citations
TL;DR: In this paper, the effect of controlled annealing on Cd-Sn eutectic lamellar structures was studied and it was shown that as-solidified features may be modified by a natural heat-treatment during directional solidification.
26 citations
TL;DR: In this paper, a Co 3.6 Fe 0.5 Cu 0.9 Ce permanent magnet alloys have been prepared by directional solidification using a modified Bridgman technique.
Abstract: Co-Fe-Cu-Ce permanent-magnet alloys have been prepared by directional solidification using a modified Bridgman technique. Samples melted at low superheat temperatures ( \DeltaT \sim 20\deg C above the melting point of about 1100°C) and solidified at moderate rates (∼2.3 cm/h) resulted in a reasonably homogeneous columnar grain structure with a preferred crystallographic orientation. The c axis is generally aligned within 15° of the growth axis. Increasing the speed of solidification led to a fine-grained structure with no texture, while decreasing the speed led to coarse columnar grains with erratic orientation. A large superheat temperature ( \DeltaT \sim 300-400\deg C resulted in a reaction of the liquid with the alumina crucible wall and led to the formation of face-centered cubic Co-rich dendrites. With the modified Bridgman technique, oriented samples 8 cm long and 2.54 cm in diameter have been prepared with good magnetic properties. After annealing at 1000°C followed by aging at 400°C, a Co 3.5 Fe 0.5 CuCe alloy exhibited values of i H c = 7000 Oe, B r = 6100 G, and (BH)_{\max} = 9.2 MG.Oe. A Co 3.6 Fe 0.5 Cu 0.9 Ce alloy exhibited values of i H c = 6000 Oe, B_{r} = 6250 G, aud (BH)_{\max} = 9.5 MG.Oe after similar treatment.
26 citations
Patent•
15 Feb 1972TL;DR: In this paper, a method of producing directionally solidified cast alloy articles is described, where a porous, shell mold having openended mold cavities is filled with molten alloy while seated on a low heat conductive surface and is allowed to cool.
Abstract: A method of producing directionally solidified cast alloy articles is disclosed wherein a porous, shell mold having openended mold cavities is filled with molten alloy while seated on a low heat conductive surface and is allowed to cool. The filled mold is then moved to a highly heat conductive surface and is reheated to a temperature above the melting range of the alloy where a unidirectional temperature gradient is established along the length of the alloy within the mold to cause directional solidification of the alloy.
14 citations
TL;DR: In this article, a floating zone technique associated to an image furnace has been used to study eutectic directional solidification of oxides, which seems to be particularly interesting because of the very high temperature gradient available at the growth interface and of the possibility of avoiding chemical reduction of the oxides.
12 citations
01 Jun 1972
TL;DR: In this paper, a fine lamellar structure with interlamellar spacings from 1 to 7μ has been produced by directional solidification of an Ag3Mg-AgMg eutectic alloy.
Abstract: A fine lamellar structure with interlamellar spacings from 1 to 7μ has been produced by directional solidification of an Ag3Mg-AgMg eutectic alloy. The tensile properties were measured as a function of test temperature, interlamellar spacing,λ, and degree of order in the Ag3Mg phase. The dependence of flow stress onλ -1/2 increased sharply with ordering of Ag3Mg and this strengthening persisted at elevated temperatures. Work hardening rate and ductility of the eutectic at low temperatures also were affected, leading to the conclusion that ordering changes the compatibility of slip across interphase boundaries.
8 citations
01 Jan 1972
TL;DR: In this article, the eutectic alloys in the Ni-In system were modeled as ribbons and lamellae of nickel-base solid solution in a matrix of e-Ni2In.
Abstract: Directional solidification of two eutectic alloys in the Ni-In system results in aligned microstructures. The eutectic at 26.5 at. pct In solidifies as ribbons and lamellae of nickel-base solid solution in a matrix of e-Ni2In. Peritectoid formation of Ni3In on cooling drastically alters the morphology, but this reaction can be suppressed by quenching. The peritectoid reaction can then be studied by isothermal heat treatments. The eutectic at 46.6 at. pct In solidifies partly as rods of e-Ni2In in a matrix of β-NiIn, partly in a lamellar morphology. Both phases transform on cooling, but because little composition change is involved, the effect on eutectic morphology is slight.
7 citations
Patent•
30 Nov 1972TL;DR: In this article, a casting apparatus for the production of directionally solidified castings comprises first, second and third chambers and valves between the first and second, and the third is a casting chamber and the second chamber is a withdrawal chamber.
Abstract: Casting apparatus for the production of directionally solidified castings comprises first, second and third chambers and valves between the first and second and second and third chambers. The first chamber holds a charge melting and pouring arrangement. The second comprises a casting chamber and the third is a withdrawal chamber so that the casting may be withdrawn in a controlled fashion from the second chamber to produce the required directional solidification.
6 citations
Patent•
08 Jun 1972
TL;DR: In this article, fine-grained polycrystalline semi-conductor bodies of chalcogenides are produced by directional solidification under the influence of sonic vibrations in the range of about 500 to about 10,000 Hz.
Abstract: Fine-grained polycrystalline semi-conductor bodies of chalcogenides are produced by directional solidification under the influence of sonic vibrations in the range of about 500 to about 10,000 Hz. The charge material is disposed in a container that is secured within a heat susceptor assembly and is melted inductively by operation of RF heating means positioned proximate to the susceptor assembly. The susceptor assembly is mechanically coupled to an electrodynamic vibrator unit so that vibrations produced by the vibrator unit are transmitted to the melt by way of the susceptor assembly and the walls of the melt container. Solidification is achieved by progressively reducing the temperature of the melt while maintaining a vertical temperature gradient across the melt container, the gradient being such that solidification proceeds upwardly in the melt.
6 citations
Patent•
30 Jun 1972
TL;DR: In this article, a method is described for the direct identification of a binary competition from a ternary melt. But this method requires a large number of min-tables.
Abstract: A METHOD IS DISCLOSED FOR THE DIRECTIONAL SOLIDIFICATION OF A BINARY COMPOSITION FROM A TERNARY MELT.
4 citations
TL;DR: In this article, the Bridgman method of directional solidification was used for the first time to produce centimeter-size single crystals of the compound KSbSe 2 and RbSbS 2.
01 Mar 1972
TL;DR: In this article, the current status of analytic and experimental studies in relation to filamentary composites and those produced by directional solidification is reviewed and attention is directed to interface structure and bond integrity, efficiency of load transfer, interface stability, and the effect of mode of loading.
Abstract: : Key to an understanding of the elastic and plastic behavior of composite materials is a characterization of the nature and role of the interface or interfacial region between phases. The current status of analytic and experimental studies is reviewed in relation to filamentary composites and those produced by directional solidification. Attention is directed to interface structure and bond integrity, efficiency of load transfer, interface stability, and the effect of mode of loading. (Author)
01 Sep 1972
TL;DR: In this article, the temperature dependence of the tensile properties was determined for the eutectic after directional solidification at rates between 0.5 and 10.6 cm/hr.
Abstract: : The temperature dependence of the tensile properties was determined for the eutectic after directional solidification at rates between 0.5 and 10.6 cm/hr. The cubic gamma' in the eutectic grows in the (110) and the orthorhombic delta in the (100). The preferred slip plane of the delta phase is parallel to the growth direction and, in response to a longitudinal stress, deformation in the delta occurred initially by twinning. The lamellar spacing which decreased with increased solidification rate was found to affect the tensile strength of the eutectic according to a Hall-Petch correlation. By decreasing the spacing by a factor of 4.7, the room temperature strength was increased by 35 percent and the strength at 2000F by 100 percent. The eutectic grown at 10.6 cm/hr possessed the phenomenal strength of 130,000 psi at 2000F. (Author)
TL;DR: In this paper, it is demonstrated that, for the case of unidirectional solidification in a silica tube, a fairly simple analysis can give calculated temperature profiles in good agreement with experiment.