| 摘要 |
PROBLEM TO BE SOLVED: To produce an aluminum material high in brightness under stable conditions by alkali etching treatment. SOLUTION: This aluminum material having >=50% reflectance is the one contg. the secondary phase particles of intermetallic compounds with <=5μm particle size by <=0.6% volume ratio, having a surface in which dimples whose diameter lines in the range of 0.1 to 100μm are formed by alkali etching, and in which, in the case the average depth of the dimples is defined as (d) (μm), the average radius of the dimples is defined as (r) (μm), the residual area ratio in the flat part is defined as (α), and the objective reflectance at the incident angle of 60 degrees is defined as R(%), the relations in the inequalities are valid within the range in which the actual value is regulated to±5 to the calculated value. At the time of the alkali etching, by finishing the etching under the conditions in which the relations in the formula are valid, the bright material having the actual reflectance in accordance with the objective value can be obtd: the inequality and formula: 1-(d/r)/tan30>=0 and [1-(d/r)/tan30]<2>⊗(1-α)+α}×92=R. By the alkali etching, high brightness can be imparted thereto.
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