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Thermodynamic Compatibility and Protective Advantages of Pure Tantalum: Cryogenic Packaging Materials for Quantum Computing

The cryogenic packaging system of quantum computing devices is a critical barrier to ensure stable operation. Its core function is to maintain an extremely low internal temperature environment and isolate external heat and interference. The thermodynamic properties, sealing performance, and corrosion resistance of the packaging material directly determine the reliability of the packaging system. Among many metallic materials, pure tantalum, with its excellent low-temperature thermodynamic stability, good sealing compatibility, and superior protective capabilities, has become an ideal material for cryogenic packaging systems in quantum computing, exhibiting significant advantages compared to commonly used packaging materials such as titanium alloys, nickel-based alloys, and aluminum alloys.

The cryogenic packaging system of quantum computing devices needs to withstand extremely large temperature gradients, from external room temperature (approximately 25°C) to internal extremely low temperatures (approximately 10 milliklvin), a temperature difference of more than 25,000 times. This extreme temperature gradient causes significant thermal expansion and contraction effects in the packaging material. If the material's coefficient of thermal expansion is too high or its thermal stability is poor, thermal stress cracks can easily occur, compromising the seal and allowing external heat to intrude, affecting the operating state of the qubits. Titanium alloys, as commonly used low-temperature structural materials, have a low coefficient of thermal expansion. However, they undergo martensitic transformation at extremely low temperatures, leading to decreased toughness and increased brittleness, making them prone to cracking during temperature cycling. Nickel-based alloys exhibit excellent high-temperature performance, but their low thermal conductivity at extremely low temperatures causes heat to accumulate internally, resulting in localized temperature increases and compromising the temperature stability of the packaging system. Aluminum alloys have a high coefficient of thermal expansion, generating significant thermal stress under temperature gradients, making them unsuitable for long-term stable packaging..

Pure tantalum exhibits unique advantages in thermodynamic properties at extremely low temperatures. First, pure tantalum has an extremely low coefficient of thermal expansion, only 6.5 × 10⁻⁶ /℃ (20-100℃), far lower than aluminum alloys (23.1 × 10⁻⁶ /℃) and titanium alloys (8.6 × 10⁻⁶ /℃). This results in minimal thermal expansion and contraction deformation under extreme temperature gradients, effectively reducing thermal stress and preventing material cracking. Secondly, pure tantalum exhibits excellent thermal conductivity stability at low temperatures. As the temperature decreases, its thermal conductivity gradually declines and stabilizes, preventing heat accumulation issues caused by sudden changes in thermal conductivity. Experiments show that at a temperature of 10 milliklvin, the thermal conductivity of pure tantalum is only 1/20th that at room temperature, effectively blocking external heat transfer and maintaining the extremely low temperature environment inside the packaging system. Furthermore, pure tantalum has a high melting point of 2996℃, demonstrating excellent high-temperature stability. Even in the event of a brief malfunction or localized temperature rise in the cooling components of the packaging system, it maintains structural stability and prevents packaging failure..

Pure tantalum also performs exceptionally well in terms of sealing performance and protection. Quantum computing cryogenic packaging systems require extremely high sealing to maintain an ultra-high vacuum environment inside. Pure tantalum possesses good plasticity and machinability, allowing it to be processed into various complex packaging structures through rolling, forging, and welding processes. The welded joints exhibit excellent strength and sealing performance, effectively preventing the permeation of gas molecules. In contrast, titanium alloys have complex welding processes, and weld joints are prone to defects such as porosity and cracks, affecting sealing performance. Nickel-based alloys have poor plasticity, making it difficult to process into complex packaging shapes. Meanwhile, pure tantalum has extremely strong chemical inertness, resisting the erosion of various corrosive gases and liquids. Even with trace amounts of refrigerant residue or impurity gases inside the packaging system, no chemical reaction occurs, ensuring the long-term stability of the packaging material. Aluminum alloys and stainless steel, on the other hand, are easily corroded during long-term use, leading to increased surface roughness and affecting sealing performance..

Currently, pure tantalum has been used in key packaging components of quantum computing devices, such as cryogenic vacuum chambers, cooling pipeline packaging, and qubit shielding. A quantum computing device manufacturer used pure tantalum to fabricate a cryogenic vacuum chamber with a leakage rate of only 1×10^-12 Pa·m³/s, far lower than the 5×10^-11 Pa·m³/s of a titanium alloy chamber, enabling it to maintain an ultra-high vacuum environment internally for extended periods. Furthermore, after 1000 temperature cycle tests, this chamber showed no cracks or deformation, demonstrating significantly superior structural stability compared to chambers made of other metal materials. Compared to expensive platinum-iridium alloys, pure tantalum not only possesses comparable low-temperature stability and protective performance but is also more affordable, making it more suitable for the large-scale production of quantum computing devices..

In summary, pure tantalum demonstrates significant advantages in low-temperature packaging systems for quantum computing due to its excellent low-temperature thermodynamic stability, good sealing compatibility, and superior protective capabilities, far surpassing commonly used metal materials such as titanium alloys, nickel-based alloys, and aluminum alloys. As quantum computing devices develop towards larger scale and industrialization, the application prospects of pure tantalum in the field of low-temperature packaging materials will become even broader, providing solid material support for ensuring the long-term stable operation of quantum computing devices..

AlloyHit specializes in producing Tantalum sheets, Tantalum rods, Tantalum wires, Tantalum targets, and Tantalum tubes in various specifications.