High-strength and high-conductivity Cu—Ag—Sc alloy and preparation method thereof

Abstract

Provided are a high-strength and high-conductivity Cu—Ag—Sc alloy and a preparation method thereof. The preparation method includes the following steps: (1) placing metal Ag and metal Sc in an electric-arc furnace and performing smelting under a vacuum condition, performing cooling to normal temperature in the furnace to obtain an Ag—Sc intermediate alloy; (2) placing the Ag—Sc intermediate alloy, an electrolytic copper and the metal Ag in an induction furnace and performing heating to 1200-1300° C. under a vacuum condition, keeping at the temperature for 10-60 min for smelting, then performing casting and cooling to normal temperature in the furnace to obtain ingots; (3) heating the ingots to 700-850° C. under an inert atmosphere, then performing water quenching to normal temperature to obtain heat-treated ingots; and (4) heating the heat-treated ingots to 400-500° C. under an inert atmosphere, then performing air cooling to normal temperature to obtain the high-strength and high-conductivity Cu—Ag—Sc.

Claims

1. A preparation method of a Cu—Ag—Sc alloy, comprising the following steps: (1) placing metal Ag and metal Sc in an electric-arc furnace and smelting the metal Ag and the metal Sc under a vacuum condition, then performing cooling to normal temperature in the electric-arc furnace to obtain an Ag—Sc intermediate alloy, wherein the Ag—Sc intermediate alloy includes 0.5-5 wt % Sc; (2) placing the Ag—Sc intermediate alloy, an electrolytic copper and metal Ag in an induction furnace and performing heating to 1200-1300° C. under a vacuum condition, keeping at the temperature for 10-60 min for smelting, then performing casting and cooling to normal temperature in the induction furnace to obtain ingots, wherein the components of the ingots are: 1-10 wt % Ag, 0.05-0.5 wt % Sc and a balance Cu; (3) heating the ingots to 700-850° C. under an inert atmosphere and keeping at the temperature for 1-15 h for heat treatment, then performing water quenching to normal temperature to obtain heat-treated ingots; and (4) heating the heat-treated ingots to 400-500° C. under an inert atmosphere and keeping at the temperature for 2-20 h for aging treatment, then performing air cooling to normal temperature to obtain the Cu—Ag—Sc alloy, wherein hardness and electrical conductivity of the Cu—Ag—Sc alloy are 88-148 HV and 83-88% IACS, respectively.

2. The method according to claim 1, wherein the vacuum condition in step (1) and step (2) is that a vacuum degree is smaller than or equal to 10.sup.−2 MPa.

3. The method according to claim 1, wherein the inert atmosphere in the step (3) is an argon atmosphere.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows a scanning electron microscope image of a Cu-2.8 Ag alloy obtained in a comparative test in an embodiment 2 of the present invention.

(2) FIG. 2 shows a scanning electron microscope image of a high-strength and high-conductivity Cu-2.8 Ag-0.2 Sc alloy in the embodiment 2 of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(3) In embodiments of the present invention, hardness is measured with a micro-hardness tester, and the electrical conductivity is tested by a four-point probe method.

(4) The metal Ag used in the embodiments of the present invention is silver bars, and the purity is 99.990-99.998%.

(5) The purity of the metal Sc used in the embodiments of the present invention is 99.75-99.99%.

(6) The purity of electrolytic copper used in the embodiments of the present invention is 99.95-99.99%.

(7) The following are preferable embodiments of the present invention.

Embodiment 1

(8) Metal Ag and metal Sc were placed in an electric-arc furnace and smelted under a vacuum condition, in which the vacuum degree is smaller than or equal to 10.sup.−2 MPa, then, cooled to normal temperature in the furnace to obtain an Ag—Sc intermediate alloy, wherein the Ag—Sc intermediate alloy includes 5 wt % Sc.

(9) The Ag—Sc intermediate alloy, an electrolytic copper and the metal Ag were placed in an induction furnace, heated to 1300° C. under a vacuum condition, in which the vacuum degree is smaller than or equal to 10.sup.−2 MPa, kept at the temperature for 15 min for smelting, then, casted and cooled to normal temperature in the furnace to obtain ingots. The components of the ingots are: 1 wt % Ag, 0.1 wt % Sc and the balance Cu;

(10) The ingots were heated to 800° C. under an inert atmosphere and kept at the temperature for 4 h for heat treatment, then, water quenched to normal temperature to obtain heat-treated ingots.

(11) The heat-treated ingots were heated to 475° C. under an argon atmosphere and kept at the temperature for 4 h for aging treatment, then, air cooled to normal temperature to obtain the high-strength and high-conductivity Cu—Ag—Sc alloy. Its hardness is 88 HV, and its electrical conductivity is 87.5% IACS.

Embodiment 2

(12) The method according to the embodiment 2 is the same as that in Embodiment 1 but has the following different points:

(13) (1) The Ag—Sc intermediate alloy includes 3 wt % Sc;

(14) (2) In an induction furnace, the temperature was heated to 1250° C., and the time was kept for 20 min for smelting. The ingots were cooled to normal temperature in the furnace. The components of the ingots are: 2.8 wt % Ag, 0.2 wt % Sc and the balance Cu;

(15) (3) The ingots were heated to 760° C., and kept at the temperature for 2 h; and

(16) (4) The ingots were aged at 450° C. and kept at the temperature for 8 h. Its hardness and electrical conductivity were 108 HV and 88% IACS, respectively.

(17) Compared with the hardness of Cu-2.8 Ag alloy without Sc, the hardness of Cu-2.8 Ag-0.2 Sc alloy was increased by 44.6%, the scanning electron microscope image of the Cu-2.8 Ag alloy was shown in FIG. 1, and the scanning electron microscope image of the high-strength and high-conductivity Cu—Ag—Sc alloy was shown in FIG. 2. According to FIGS. 1 and 2, the Cu-2.8 Ag-0.2 Sc alloy only had a fine uniform continuous Ag precipitates, but the Cu-2.8 Ag alloy had coarse discontinuous Ag precipitates.

(18) The hardness of the Cu-2.8 Ag-0.2 Sc alloy was higher than that of the Cu-2.8 Ag alloy. After aging treatment at 450° C., the hardness of the Cu-2.8 Ag-0.2 Sc alloy was 108HV and increased 44.6% relative to the Cu-2.8 Ag alloy under the same condition. From the scanning electron microscope image, the Cu-2.8 Ag-0.2 Sc alloy only had fine uniform continuous Ag precipitates, but the Cu-2.8 Ag alloy had coarse discontinuous Ag precipitates (FIG. 1 and FIG. 2).

Embodiment 3

(19) The method according to the embodiment 3 is the same as that in Embodiment 1 but has the following different points:

(20) (1) The Ag—Sc intermediate alloy includes 5 wt % Sc;

(21) (2) In an induction furnace, the temperature was heated to 1250° C., and the time was kept for 15 min for smelting. The ingots were cooled to normal temperature in the furnace. The components of the ingots are: 3 wt % Ag, 0.4 wt % Sc and the balance Cu;

(22) (3) The ingots were heated to 760° C., and kept at the temperature for 10 h; and

(23) (4) The ingots were aged at 450° C. and kept at the temperature for 4 h. Its hardness and electrical conductivity were 115 HV and 84% IACS, respectively.

Embodiment 4

(24) The method according to the embodiment 4 is the same as that in Embodiment 1 but has the following different points:

(25) (1) The Ag—Sc intermediate alloy includes 2 wt % Sc;

(26) (2) In an induction furnace, the temperature was heated to 1300° C., and the time was kept for 20 min for smelting. The ingots were cooled to normal temperature in the furnace. The components of the ingots are: 7 wt % Ag, 0.07 wt % Sc and the balance Cu;

(27) (3) The ingots were heated to 760° C., and kept at the temperature for 6 h; and

(28) (4) The ingots were aged at 450° C. and kept at the temperature for 16 h. Its hardness and electrical conductivity were 148 HV and 83% IACS, respectively.