NiMoW and NiCoCr alloys
Research techniques: Micro/ nano-scale evaluation, elevated temperature evaluation, fatigue, creep and fracture evaluation, material imaging and characterization, etc.
The exploration of alloy materials by combining multiple elements to forge a single alloy material has enabled us to discover improved material properties and stability as compared to single element metals. For example, steel as one of the most commonly used metallic alloy is forged from the two elements iron and carbon. Compared to iron, steel possesses higher strength, durability and anti-corrosive properties and have been widely used in many structural applications and consumer products.
Accordingly, the development of materials that possess improved mechanical, functional properties at wider temperature range in addition to the ability to be shaped on micro-scale would greatly expand the design space for the future electronic systems. Metallic materials are especially attractive in micro-electromechanical system (MEMS) applications that require high density, electrical and thermal conductivity. The currently developed materials either possessed the required strength, but are held back by their thermal instability and time-dependent deformations that deteriorates the material performance, or vice versa.
Therefore, Sim et al. developed NiMoW films by introduced the element molybdenum into NiW alloys with the intention to lower the stacking fault energy and residual stress of the films. The NiMoW films deposited as single-phase nanotwinned solid solutions, possess remarkably improved dimensional stability and ultra-high tensile strengths of approximately 3 GPa, surpassing all the other available nanotwinned materials. In addition, films annealed at 1,000℃ for 1 h were found to exhibit strength greater than 1.2 GPa and near 10% tensile ductility. An excellent balance between mechanical properties and dimensional stability make sputter deposited NiMoW alloys promising structural materials for MEMS applications, hard and high-strength coatings, corrosion resistive coatings, etc. With the aim to industrialize this material, we focus on further enhancing and standardizing the stability of the material and its fabrication parameters. Moreover, in-depth investigation is conducted to evaluate its material performance in cyclic, creep, repeated stress relaxation tests, and at elevated temperatures.
On the other hand, NiCoCr medium entropy alloys (MEA) possess desirable fracture toughness and material stability at temperatures as low as 77 K, making it an interesting candidate for a number of cryogenic applications such as liquid gas storage, coatings for space applications etc. However, extensive usage of this material is currently limited due to a high cost. Hence, we algin our efforts to understand its material behaviors in the mico/ nano-scale as it provides a higher cost and time efficiency in integrating this materials into future applications.
The exploration of alloy materials by combining multiple elements to forge a single alloy material has enabled us to discover improved material properties and stability as compared to single element metals. For example, steel as one of the most commonly used metallic alloy is forged from the two elements iron and carbon. Compared to iron, steel possesses higher strength, durability and anti-corrosive properties and have been widely used in many structural applications and consumer products.
Accordingly, the development of materials that possess improved mechanical, functional properties at wider temperature range in addition to the ability to be shaped on micro-scale would greatly expand the design space for the future electronic systems. Metallic materials are especially attractive in micro-electromechanical system (MEMS) applications that require high density, electrical and thermal conductivity. The currently developed materials either possessed the required strength, but are held back by their thermal instability and time-dependent deformations that deteriorates the material performance, or vice versa.
Therefore, Sim et al. developed NiMoW films by introduced the element molybdenum into NiW alloys with the intention to lower the stacking fault energy and residual stress of the films. The NiMoW films deposited as single-phase nanotwinned solid solutions, possess remarkably improved dimensional stability and ultra-high tensile strengths of approximately 3 GPa, surpassing all the other available nanotwinned materials. In addition, films annealed at 1,000℃ for 1 h were found to exhibit strength greater than 1.2 GPa and near 10% tensile ductility. An excellent balance between mechanical properties and dimensional stability make sputter deposited NiMoW alloys promising structural materials for MEMS applications, hard and high-strength coatings, corrosion resistive coatings, etc. With the aim to industrialize this material, we focus on further enhancing and standardizing the stability of the material and its fabrication parameters. Moreover, in-depth investigation is conducted to evaluate its material performance in cyclic, creep, repeated stress relaxation tests, and at elevated temperatures.
On the other hand, NiCoCr medium entropy alloys (MEA) possess desirable fracture toughness and material stability at temperatures as low as 77 K, making it an interesting candidate for a number of cryogenic applications such as liquid gas storage, coatings for space applications etc. However, extensive usage of this material is currently limited due to a high cost. Hence, we algin our efforts to understand its material behaviors in the mico/ nano-scale as it provides a higher cost and time efficiency in integrating this materials into future applications.
Read more in our publications:
[1] Park, Y., Choi, S., Ryou, K., Park, J., Choi, W. S., Ko, W. S., Choi, P. P., Sim, G. D. (2024). Effect of compositional undulation on the mechanical behavior of atomic-scale planar-faulted Ni-Mo-W films. Materials Science and Engineering: A, 147250.
[2] Park, J., Park, Y., Choi, S., Lee, Z. F., Sim, G. D. (2024). Fatigue behavior of freestanding nickel-molybdenum-tungsten thin films with high-density planar faults. Nanoscale.
[3] Kim, K., Park, S., Kim, T., Park, Y., Sim, G. D., & Lee, D. (2022). Mechanical, electrical properties and microstructures of combinatorial Ni-Mo-W alloy films. Journal of Alloys and Compounds, 919, 165808.
[4] Sim, G. D., Krogstad, J. A., Xie, K. Y., Dasgupta, S., Valentino, G. M., Weihs, T. P., & Hemker, K. J. (2018). Tailoring the mechanical properties of sputter deposited nanotwinned nickel-molybdenum-tungsten films. Acta Materialia, 144, 216-225.
[5] Sim, G. D., Krogstad, J. A., Reddy, K. M., Xie, K. Y., Valentino, G. M., Weihs, T. P., & Hemker, K. J. (2017). Nanotwinned metal MEMS films with unprecedented strength and stability. Science advances, 3(6), e1700685.
[1] Park, Y., Choi, S., Ryou, K., Park, J., Choi, W. S., Ko, W. S., Choi, P. P., Sim, G. D. (2024). Effect of compositional undulation on the mechanical behavior of atomic-scale planar-faulted Ni-Mo-W films. Materials Science and Engineering: A, 147250.
[2] Park, J., Park, Y., Choi, S., Lee, Z. F., Sim, G. D. (2024). Fatigue behavior of freestanding nickel-molybdenum-tungsten thin films with high-density planar faults. Nanoscale.
[3] Kim, K., Park, S., Kim, T., Park, Y., Sim, G. D., & Lee, D. (2022). Mechanical, electrical properties and microstructures of combinatorial Ni-Mo-W alloy films. Journal of Alloys and Compounds, 919, 165808.
[4] Sim, G. D., Krogstad, J. A., Xie, K. Y., Dasgupta, S., Valentino, G. M., Weihs, T. P., & Hemker, K. J. (2018). Tailoring the mechanical properties of sputter deposited nanotwinned nickel-molybdenum-tungsten films. Acta Materialia, 144, 216-225.
[5] Sim, G. D., Krogstad, J. A., Reddy, K. M., Xie, K. Y., Valentino, G. M., Weihs, T. P., & Hemker, K. J. (2017). Nanotwinned metal MEMS films with unprecedented strength and stability. Science advances, 3(6), e1700685.
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Updated on 2025.04.05
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