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[논문게재] Combined experimental and computational investigation of precipitation behaviour and mechanical properties in a novel Cu–Ni–Si–Co alloy: effect of solution treatment temperature

관리자 │ 2024-10-04

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410
  • Author: H.Nam†, J.Choi
  • †
  • , 
    • H.Kim, J.Lee* and J.Kim*


    Title: Combined experimental and computational investigation of precipitation behaviour and mechanical properties in a novel Cu–Ni–Si–Co alloy: effect of solution treatment temperature


    Journal: Materials Technology

    Year: 2024


    Impact factor: 2.9


    Abstract:

    Cu alloys are extensively utilized in electronics for heat exchangers, electrical conductors, automotive connectors, and electrical contacts. To meet the demands of miniaturization, these alloys must exhibit enhanced strength and electrical conductivity. We investigated the microstructural and precipitation properties of the Cu–Ni–Si–Co alloy at the solution treatment temperature (1,050°C). We subjected the alloy to cold rolling and ageing. The secondary-phase particles dissolved completely at higher temperatures, increasing the concentrations of the Ni, Si, and Co solutes within the Cu matrix. This enhanced supersaturation facilitated higher precipitation during ageing, resulting in fine (Ni,Co)2Si precipitates with a number density of 12.3 × 1010 cm-2. The alloy was strengthened by the Orowan mechanism and exhibited good electrical conductivity. Moreover, nanoscale (Ni,Co)2Si precipitates were formed. We achieved the highest hardness of 251 hV and an electrical conductivity (EC) of 51% International Annealed Copper Standard (IACS).


    Figure 1. SEM images of the Cu–1.3Ni–0.6Si–1.0Co alloys after solution treatment (a) at 950°C and (b) at 1,050°C for 30 s. (c) EDS result for the secondary phase particles in (a).

    Figure 2. TEM images of the Cu–1.3Ni–0.6Si–1.0Co alloy. (a) and (b) BF images and (c) HR–TEM image and corresponding FFT image of fine precipitates along [001]Cu at 1,050°C. (d) BF image, (e) DF image, and (f) HR–TEM image and FFT image of coarse precipitates along [001]Cu at 950°C. (g) BF image, (h) DF image, and (i) HR–TEM image and FFT image of fine precipitates along [001]Cu at 1,050°C.

    Figure 3. TEM images of the Cu–1.3Ni–0.6Si–1.0Co alloy solution treated at (a) 950°C and (b) 1,050°C for 30 s.

    Figure 4. Atomic models for the interfaces (a) between Cu (110) and (Ni0.5Co0.5)2Si (001) Ni-terminated surfaces and (b) between Cu (110) and (Ni0.5Co0.5)2Si (010) surfaces. Calculated interfacial energies of the (Ni0.5Co0.5)2Si precipitate (c) with Cu (110) and (d) with (Ni0.5Co0.5)2Si itself.

    Figure 5. Variation of hardness of the Cu–1.3Ni–0.6Si–1.0Co alloys solution treated at different temperatures, followed by a two-stage ageing process (520°C for 1 h in the first stage and 420°C for 0–24 h in the second stage).

    Figure 6. Variation of electrical conductivity of the Cu–1.3Ni–0.6Si–1.0Co alloys solution treated at different temperatures, followed by a two-stage ageing process (520°C for 1 h in the first stage and 420°C for 0–24 h in the second stage).
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