Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
Crystal Orientations and Reflective Properties of the Coarse-grained Aluminum Alloy Plate for Interior Materials
Masateru NoseTakekazu NagaeMasaru YokotaShigeoki SajiToshihide HayashiYasuyuki Nakamura
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1998 Volume 62 Issue 10 Pages 887-892

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Abstract

The aluminum alloy (JIS-A1070: 99.7%Al) plate showing a large grain patterns is used as an interior material. We investigated the relationship between the optical properties to surface morphology and crystal orientations of this type of aluminum plate. The annealed sample having coarsened grains (5-20 mm diameter) was etched with a mixture of sulfuric acid and hydrochloric acid. The crystals are classified into two types from the reflective properties by the measurement of regular reflectance for each crystal: one is the crystal which has smooth surface and shows high regular reflectance. The other one is the crystal which has ∼2 μm high jagged surfaces such as a wavy pattern: the regular reflectance is less than a few % on the surface of the crystal. (The main reflective face of this type of crystal should be the oblique plane of jag.) The former type of crystal is named “type A” and the latter is “type B” provisionally. Some of these types of crystals were cut out and their crystal orientations were measured by using an Xray diffractometer having the 3-axis goniometer. As a result, type A crystals have the (310) or (100) plane and all of type B have the (110) plane, which are parallel or inclined less than 10 degrees to the plate surface. Furthermore, the longish direction of wavy jag is virtually parallel to the ⟨100⟩ direction of type B crystal. Since the incident light on type B crystal should be mainly reflected on the oblique plane, the brilliancy of each type B crystal depends on the direction of the wavy pattern, namely on the ⟨100⟩ direction. From these results, it is important for a interior material to have a properly dispersed direction of ⟨100⟩ with a view to showing a multiform reflection. Accordingly, the materials composed of strongly oriented crystals are found to be unsuitable for interior materials.

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