PHOTOLUMINESCENT ALUMINUM ALLOY AND PHOTOLUMINESCENT ALUMINUM ALLOY DIE-CAST MATERIAL

Abstract

The present invention provides a photoluminescent aluminum alloy which exhibits high mechanical properties and which suppresses, to a high degree, the occurrence of color unevenness in cases where a tungsten-containing aluminum alloy die-cast material is subjected to anodization. Also provided is a photoluminescent aluminum alloy die-cast material produced using the photoluminescent aluminum alloy. This aluminum alloy contains 0.5-3.0 mass % of Mn, 0.3-2.0 mass % of Mg, 0.01-1.0 mass % of W and 1.0-3.0 mass % of Zn, with the remainder comprising aluminum and unavoidable impurities.

Claims

1. An aluminum alloy comprises Mn: 0.5 to 3.0% by mass, Mg: 0.3 to 2.0% by mass, W: 0.01 to 1.0% by mass, Zn: 1.0 to 3.0% by mass, with the remainder comprising aluminum and unavoidable impurities.

2. The aluminum alloy according to claim 1, wherein a content of the Mn is 1.0 to 2.0% by mass, a content of the Mg is 0.5 to 1.5% by mass, and a content of Zn is 1.5 to 2.5% by mass.

3. The aluminum alloy according to claim 1, wherein further contains one or more of Ti: 0.01 to 0.5% by mass, B: 0.001 to 0.2% by mass, and Zr: 0.01 to 0.5% by mass.

4. An aluminum alloy die-cast material comprising the aluminum alloy according to claim 1, which has a tensile property of 0.2% proof stress of 100 MPa or more.

5. The aluminum alloy die-cast material according to claim 4, wherein a Vickers hardness is 60 or more.

6. The aluminum alloy die-cast material according to claim 4, wherein a granular crystal region formed by primary crystal a particles having a maximum ferret diameter of 10 μm or more occupies 90% or more of the surface area ratio of the member surface.

7. The aluminum alloy die-cast material according to claim 4, which is provided with an anodic oxide film of about 5 μm formed by anodizing treatment without dyeing by using a sulfuric acid bath, and, in the color measurement of the surface of the anodic oxide film, when using the CIE standard illuminant D65 as the light source, the L* value is 70 or more, the a* value is 0 to 2, and the b* value is 1 to 4.

Description

EXAMPLES

Example 1

[0077] In Table 1, an aluminum alloy having the composition described as Example 1 was melted and produced, and die casting was performed at the casting pressure of 120 MPa, the molten metal temperature of 730° C. and the die temperature of 170° C. The die shape is a plate shape of 55 mm×110 mm×3 mm. The unit of the numerical values shown in Table 1 is % by mass concentration.

TABLE-US-00001 TABLE 1 Mn Mg W Zn Ti Cu Fe Zn Al Ex. 1 1.4 1.0 0.08 2.0 0.05 — — — Bal. Com. Ex.1 1.4 — 0.08 — 0.05 — — — Bal. Com. Ex.2 2.2 1.0 0.08 — 0.07 — — — Bal. Com. Ex.3 0.18 0.12 — 10.22 0.04 2.65 0.81 0.48 Bal.

[0078] When the No. 14B test piece specified in JIS-Z2241 was collected from the obtained aluminum alloy die-cast material and subjected to a tensile test at room temperature, the 0.2% proof stress and Vickers hardness were as shown in Table 2.

TABLE-US-00002 TABLE 2 0.2% proof stress Vickers hardness (Mpa) (HV) Ex. 1 111 77 Com. Ex.1 62 38 Com. Ex.2 94 60 Com. Ex.3 150 82

[0079] The obtained aluminum alloy die-cast material was subjected to the blast treatment by using fine particles having a particle size of 125 to 250 μm composed of ZrO.sub.2, SiO.sub.2, or the like, and applying the injection pressure of 0.4 MPa, the degreasing treatment by using a halogenated hydrocarbon as a solvent, after a shower at a temperature of 72° C. for about 10 seconds, and performing the steam injection for about 1 minute, the desmutting treatment by using HNO.sub.3 having a concentration of 200 g/l as a bath solution, immersing at room temperature for about 1 minute, and irradiating with ultrasonic waves, the chemical polishing treatment by immersing in a mixed solution of phosphoric acid and nitric acid at 95° C. for about 5 minutes, the anodizing treatment by using H.sub.2SO.sub.4 having a concentration of 180 g/l as a solution, and subjecting to energization treatment at a solution temperature of 18° C., the current density of 150 A/m.sup.2 for 33 minutes and 20 seconds, and the pore sealing treatment by using a nickel acetate-based pore-sealing agent as a solution, and immersing in the solution of 95° C. for about 30 minutes, in this order to obtain an aluminum alloy die-cast material with an anodic oxide film.

[0080] The L* value, a* value, and b* value (CIELab color space) of the obtained aluminum alloy die-cast material with the anodic oxide film were measured by the color measuring method specified in JISZ8781. Further, the presence or absence of color unevenness was determined with the naked eyes, and evaluated according to the rule where when there was no color unevenness, ◯ was given, when there was slight color unevenness, Δ was given, and when there was some color unevenness, × was given. In addition, with respect to the region where the presence or absence of color unevenness was visually evaluated, the evaluation was performed whether or not the granular crystal region exceeded 90% of the surface area of the member. Specifically, after removing the anodic oxide film in the target region by polishing, etching was performed and then observation was performed with an optical microscope. In addition, the granular crystal region was identified from the obtained photograph of the optical microscope, and the area ratio with respect to the entire observed image was calculated. When the area ratio of the granular crystal region exceeded 90%, it was judged as ◯, and when did not exceed, it was judged as ×.

TABLE-US-00003 TABLE 3 Evaluation of Light granular Color source L* a* b* crystal area unevenness Ex. 1 D65 83.76 0.68 2.12 ○ ○ Com. Ex.1 D65 82.26 0.87 2.96 ○ ○ Com. Ex.2 D65 82.75 0.8 2.59 x Δ Com. Ex.3 D65 36.56 0.62 2.59 x x

Comparative Example 1

[0081] A test piece was collected in the same manner as in Example 1 except that the melting material was adjusted so as to have the components described as Comparative Example 1 in Table 1, and when the 0.2% proof stress was measured, the values shown in Table 2 were obtained.

[0082] Further, as a result of anodizing treatment and color measurement under the same conditions as in Example 1, evaluations of L* value, a* value, b* value (CIELab color space), color unevenness, and granular crystal region were the values shown in Table 3.

Comparative Example 2

[0083] A test piece was collected in the same manner as in Example 1 except that the melting material was adjusted so as to have the components described as Comparative Example 2 in Table 1, and when the 0.2% proof stress was measured, the values shown in Table 2 were obtained.

[0084] Further, as a result of anodizing treatment and color measurement under the same conditions as in Example 1, evaluations of L* value, a* value, b* value (CIELab color space), color unevenness, and granular crystal region were the values shown in Table 3.

Comparative Example 3

[0085] As a result of anodizing treatment and color measurement under the same conditions as in Example 1 except that the melting material was adjusted so as to have the components described as Comparative Example 3 in Table 1, evaluations of L* value, a* value, b* value (CIELab color space), color unevenness, and granular crystal region were the values shown in Table 3. The composition of Comparative Example 3 corresponds to ADC12.

[0086] From Table 2, the aluminum alloy die-cast material of the present invention has both a tensile property of 0.2% proof stress of 100 MPa or more and a hardness of 60 HV or more. On the other hand, though the aluminum alloy die-cast material of Comparative Example 3 has a high tensile property of 0.2% proof stress and Vickers hardness, the aluminum alloy die-cast materials of Comparative Examples 1 and Comparative Example 2 have a tensile property of 0.2% proof stress of less than 100 MPa and the hardness of less than 60 HV.

[0087] Further, from Table 3, the aluminum alloy die-cast material with the anodic oxide film of about 5 μm of the present invention has the values within the range where the L* value is 70 or more, the a* value is 0 to 2, and the b* value is 1 to 4, in the color measurement of the surface of the anodic oxide film, when using the CIE standard illuminant D65 as the light source. On the other hand, the aluminum alloy die-cast materials of the comparative examples with the anodic oxide film of about 5 μm has the a* value and the b* value within the range, but in Example 3, the L* value is significantly low.

[0088] From the above results, it is understood that, in an aluminum alloy containing an appropriate amount of tungsten, an aluminum alloy die-cast material having 0.2% proof stress of 100 MPa or more, and hardness of 60 HV or more, in addition to good brightness (L* value), hue and saturation (a* value, b* value), no color unevenness is only the aluminum alloy die-cast material of Example 1 where the addition amounts of Mn, Mg and Zn which are elements that improve the mechanical properties of the aluminum alloy die-cast material are strictly controlled.