Effect of Die Temperature on Tensile Property of Rheocast Phosphor Bronze

Semi-solid slurry of phosphor bronze with fine solid granules for rheocasting was tried to make by passing the low-superheat melt through an opening between a rotating regular octagonal rotor and a circumscribed chill block. The effect of rotational speed on the structure of a solidified small ingot was mainly investigated. The ingot structures were changed from the dendrite of rotor-free condition to the rosette at the rotational speed of 50rpm, and the granular with a mean size of about 50μm at higher than150rpm. The slurries made at 150rpm were rheocast to a cylindrical shape cavity within a die kept at different temperatures from 573 to 1173K by the use of a high pressure casting machine. Microstructures of rheocast cylindrical shape products were granular at the die temperatures lower than 773K and changed to grained one as like recrystallized at higher than 973K. Together with the microstructure change, poor tensile ductility less than 3% at the lowest die temperature was improved up to about 60% at 973K.

Effect of Die Temperature on Tensile Property of Rheocast Phosphor Bronze

Semi-solid slurry of phosphor bronze with fine solid granules for rheocasting was tried to make by passing the low-superheat melt through an opening between a rotating regular octagonal rotor and a circumscribed chill block. The effect of rotational speed on the structure of a solidified small ingot was mainly investigated. The ingot structures were changed from the dendrite of rotor-free condition to the rosette at the rotational speed of 50rpm, and the granular with a mean size of about 50μm at higher than150rpm. The slurries made at 150rpm were rheocast to a cylindrical shape cavity within a die kept at different temperatures from 573 to 1173K by the use of a high pressure casting machine. Microstructures of rheocast cylindrical shape products were granular at the die temperatures lower than 773K and changed to grained one as like recrystallized at higher than 973K. Together with the microstructure change, poor tensile ductility less than 3% at the lowest die temperature was improved up to about 60% at 973K.

Effect of Polygonal Rotor Process on Solidification Structure of Lead-Free Bismuth Bronze

Semi-solid slurry with fine solid granules for rheocasting was made from lead-free bismuth bronze by passing the low-superheat melt through an opening between a rotating regular octagonal rotor and a circumscribed chill block. We mainly investigated the effect of rotational speed on the structure of a solidified small ingot. The ingot structures changed from the dendrite of rotor-free condition to the rosette at the rotational speed of 50rpm and to the granular with a mean grain size of about 50m at higher than100 rpm. If the slurry made at 100rpm was rheocast to a disk shape by the use of a high pressure casting machine, the disk had almost uniform granular structures from the center to the edge regions.

The Effect of Casting Variables on the Structure of Hypereutectic Al-Si Alloys

The effect of size refinement of primary silicon and modification of eutectic silicon, separately and simultaneously, on microstructure of hypereutectic Al-20wt%Si has been investigated under different casting conditions. Results showed that number per unit volume of primary silicon particles was doubled by inoculation with 0.02% phosphorus in the alloy with 0.0015% phosphorus already in it, whereas 70% of a small ingot (40×35 mm) became modified eutectic, and the formation of primary silicon was suppressed, on adding 0.1% strontium. Simultaneous addition of phosphorus and strontium still refined the primary silicon but did not modify the eutectic. Addition of strontium alone caused roughening of the primary silicon, exemplified by increased undercooling registered on the cooling curve. Also crystallographic relationships between polyhedral primary silicon particles have been investigated by Electron Back Scattered Diffraction (EBSD).

The Broach coin-hoard as evidence of the import of valuta across the Arabian Sea during the 13th and 14th centuries

The Broach (Bharoch) hoard found in 1882, though its publication is statistically incomplete, offers evidence of the movement and import of valuta into western India during the 13th and more particularly the 14th century. Broach and Cambay were the principal ports of Gujarat during this period. The hoard, found in a brass pot, consisted of 448 gold coins, besides pieces of coins and a small ingot, and about 1,200 silver coins and pieces. The coinages represented are those of Genoa, Venice, Egypt, Armenia, Persia, southern Arabia and the Dehfi Sultanate. With the exception of two 12th-century coins the dates of minting fall between A.D. 1260 and 1382, which we may take to be the approximate date of burial.

Micro-crystalline structure of platinum

The crystalline structure of platinum does not appear to have been studied, although it forms an interesting subject for investigation. A small ingot of pure platinum was obtained for the experiments. A section was cut therefrom and machined to 5/16 inch square and 1/10 inch in thickness. The section was then carefully polished and etched in aqua regia of the following strength :— 4 parts of hydrochloric acid (sp. gr. 1·2). 1 part of nitric acid (sp. gr. 1·42).