Silver alloy with improved mechanical properties

Abstract

The present invention discloses silver alloy composition consisting of at least 90.0% silver, 0.01-1.5% by weight of each of zirconium, magnesium, titanium and the balance copper with improved mechanical properties. The alloying metal in silver alloy impart both high “as cast” and “60% cold worked” hardness with workable springiness, reduced specific gravity and is resistant to wear and tear.

Claims

1. An alloy composition comprising; i. at least 92.5% by weight of silver; ii. 0.01 to 1.5% by weight of zirconium; iii. 0.01 to 1.5% by weight of magnesium; iv. 0.01 to 1.5% by weight of titanium; wherein the balance is copper; and wherein the alloy composition has an “as cast” Vickers hardness of 130 HV to 150 HV.

2. The alloy composition as claimed in claim 1, comprising 92.5% to 99.5% by weight of silver.

3. The alloy composition as claimed in claim 2, comprising; i. 92.5% by weight of silver; ii. 0.15% by weight of zirconium; iii. 0.15% by weight of magnesium; iv. 0.15% by weight of titanium; and v. 7.05% by weight of copper.

4. The alloy composition as claimed in claim 2, comprising; i. 97% by weight of silver; ii. 0.15% by weight of zirconium; iii. 0.15% by weight of magnesium; iv. 0.15% by weight of titanium; and v. 2.55% by weight of copper.

5. The alloy composition with improved mechanical properties as claimed in claim 2, wherein the alloy composition has increased elastic deflection, as compared to a comparative alloy consisting of 92.5% to 99.5% by weight of silver, with the balance of the comparative alloy being copper.

6. The alloy composition with improved mechanical properties as claimed in claim 3, wherein the alloy composition has increased elastic deflection, as compared to a comparative alloy consisting of 92.5% by weight of silver and 7.5% by weight of copper.

7. The alloy composition with improved mechanical properties as claimed in claim 4, wherein the alloy composition has increased elastic deflection, as compared to a comparative alloy consisting of 97% by weight of silver and 3% by weight of copper.

8. An alloy composition comprising; i. at least 92.5% by weight of silver; ii. 0.01 to 1.5% by weight of zirconium; iii. 0.01 to 1.5% by weight of magnesium; iv. 0.01 to 1.5% by weight of titanium; wherein the balance is copper; and wherein cold work hardening (60%) of the alloy composition produces a Vickers hardness of 150 HV to 180 HV.

9. An alloy composition comprising; i. at least 92.5% by weight of silver; ii. 0.01 to 1.5% by weight of zirconium; iii. 0.01 to 1.5% by weight of magnesium; iv. 0.01 to 1.5% by weight of titanium; wherein the balance is copper; and wherein the alloy composition has a specific gravity of 9.95 g/cc to 10.15 g/cc.

Description

EXAMPLE 1

(1) The alloy containing at least 90% by weight of silver and alloying metals zirconium, titanium, magnesium and copper in varying proportion as shown in example 2 and 3 below were prepared by solid-solution method. For comparative purpose, the conventional silver alloy was prepared by similar method.

(2) Accordingly, to the fine silver was added the alloying metals titanium, zirconium, magnesium and copper, mixed and melted in vacuum furnace to form the melt. The obtained melt was mold casted and cooled. The “as cast” alloy was further cold worked to 60% at room temperature to obtain the alloy,

EXAMPLE 2

(3) Composition of the Present Alloy: Silver (Ag)—92.5% by weight Titanium (Ti)—0.15% by weight Zirconium (Zr)—0.15% by weight Magnesium (Mg)—0.15% by weight Copper (Cu)—7.05% by weight

(4) Conventional Sterling Silver: Silver (Ag)—92.5% by weight Copper (Cu)—7.5% by weight

(5) TABLE-US-00001 Present Sterling Conventional Sterling Properties Silver Alloy Silver Hardness “as cast” 140-145-146 114-121-123 60% cold work Hardening 166-171-173 133-138-140 Wear Resistance Wt. before Test- Wt. before Test- Size: 10*10*0.8 mm 0.800 gm 0.830 gm Wt. after Test- Wt. after Test- 0.795 gm 0.815 gm Percentage Loss: 0.625% of the 1.8% of the Keeping all pieces in total weight total weight polishing media (1 day) Specific Gravity 9.98 g/cc (mean) 10.36 g/cc Reduction In Gravity % 3.668 Springiness Test 325 gm*11.7 mm 250 gm*10.5 mm (with cantilever configuration) W = 10.2, T = 1.01, L = 85 mm, Load vs. Deflection (max)

(6) Specific Gravity: The results depict that the mean specific gravity of the present sterling silver alloy is significantly reduced. While the specific gravity of the conventional sterling silver alloy is 10.36 g/cc the mean specific gravity of the present sterling silver alloy is 9.98 g/cc which is 3.668% lesser than the conventional sterling silver alloy.

(7) Hardness: The high “as cast” hardness as well as the cold worked (60%) hardness of the present sterling silver alloy is significantly higher than the conventional sterling silver alloy. The improved hardness of the present sterling silver alloy makes the present alloy a promising commercial alloy as the conventional sterling silver alloy is soft for jewellery applications.

(8) Springiness: Higher deflection is observed even for higher grammage or sterling silver alloy of the present invention indicating enhanced springiness of the silver alloy useful in manufacture of jewellery articles.

EXAMPLE 3

(9) Composition of the present Alloy: Silver (Ag)—97.0% by weight Titanium (Ti)—0.15% by weight Zirconium (Zr)—0.15% by weight Magnesium (Mg)—0.15% by weight Copper (Cu)—2.55% by weight

(10) Conventional Silverware: Silver (Ag)—970% h weight Copper (Cu)—3.0% by weight

(11) TABLE-US-00002 Present Silver Conventional Properties Alloy Silverware Hardness “as cast” 133-135-145 90-92-102 60% cold work Hardening 150-150-152 113-115-117 Wear Resistance Wt. before Test- Wt. before Test- Size: 10*10*0.8 mm 0.790 gm 0.800 gm Wt. after Test- Wt. after Test- 0.780 gm 0.783 gm Percentage Loss: 1.26% of the 2.12% of the Keeping all pieces in total weight total weight polishing media (1 day) Specific Gravity 10.12 g/cc (mean) 10.44 g/cc Reduction In Gravity % 3.065 Springiness Test 280 gm*10.1 mm 250 gm* 9.6 mm (with cantilever configuration) W = 10.2, T = 1.01, L = 85 mm, Load vs. Deflection (max)

(12) Specific Gravity: The results depict that the mean specific gravity of the present silver alloy comprising 97% by weight of silver is significantly reduced. While the specific gravity of the conventional silver alloy (97% by weight of silver) is 10.44 g/cc the mean specific gravity of the present silver alloy (97% by weight of silver) is 10.12 g/cc which is 3.065% lesser than the conventional silver

(13) Hardness: The high “as cast” hardness as well as the cold work (60%) hardness of the present silver alloy (97% by weight of silver) is significantly higher than the conventional silver alloy (97% by weight of silver). The improved hardness of the present silver alloy makes the present alloy a promising commercial alloy.

(14) Springiness: Higher deflection is observed even for higher grammage of silver alloy of the present invention.