Desenvolvimento de um dispositivo para obtenção de monocristais de ligas à base de cobre

Abstract

This paper describes the drawing, construction and optimization of a device, which can be used to obtain single crystals of different metallic materials with melting point from 550 to 1050 o C. Components of ease obtaining and of low cost were used. The device was based on the modified Bridgman technique and it was used to obtain single crystals of copper-based alloys. The temperature axial profiles and a difference less then 1% in the temperature between the wall and the center of the ceramic tube in the critical region for obtaining single crystals of good quality indicated that the oven presents a good thermal stability. Single crystals of CuZnAl and CuAlAg alloys of good quality were growth and characterized using optical microscopy and Laüe X-ray back reflection.

Laüe back-reflection method for crystallographic orientation of a martensitic Cu-Zn-Al single crystal of the monoclinic system

“…The blister was placed in a modified Bridgman's furnace constructed in our laboratory 12 and the material was slowly run through the longitudinal axis of the furnace where the alloy was remelted and the single crystal was obtained.…”

“…Due to the difficulties to buy single crystals of copper-based alloys with a desired composition, a furnace previously described 11 was modified and constructed 12 in our laboratories to obtain single crystals based on the Bridgman's method 13 . Our studies began with an easier crystallographic system, a single crystal β phase Cu-ZnAl alloy, which belongs to the DO 3 ordered structure.…”

“…Our studies began with an easier crystallographic system, a single crystal β phase Cu-ZnAl alloy, which belongs to the DO 3 ordered structure. Single crystals were orientated in the (111), (110) and (100) crystallographic planes 12,14 , using the Laüe back-reflection method 15,16 . Considering our interest in shape memory copper-based alloys [17][18][19] , simultaneously to the β phase Cu-Zn-Al preparation, martensitic Cu-Zn-Al single crystals were also obtained.…”

Desenvolvimento de microcélula eletroquímica para estudos de microrregiões

“…1 Uma alternativa escolhida por nosso grupo para obter resultados mais significativos de ligas metálicas e de metais não nobres foi a realização de estudos em monocristais orientados. 2,3 No entanto, a obtenção de monocristais orientados geralmente demanda tempo, exige equipamentos específicos além de conhecimentos e habilidades do operador. Somado a isso, alguns materiais são difíceis de obter corpos monocristalinos por meio de técnicas convencionais.…”

“…2,3 No entanto, a obtenção de monocristais orientados geralmente demanda tempo, exige equipamentos específicos além de conhecimentos e habilidades do operador. Somado a isso, alguns materiais são difíceis de obter corpos monocristalinos por meio de técnicas convencionais.…”