1J85 Alloy

1J85 (internationally recognized as Ultra-Supermalloy) is an advanced iron-nickel-molybdenum (Fe-Ni-Mo) based ultra-high-precision soft magnetic alloy, representing the top tier of the Permalloy family. It is specifically engineered for ultra-low-frequency, ultra-weak magnetic field applications demanding unrivaled magnetic permeability stability, extremely low coercivity, and minimal magnetic hysteresis loss. Unlike 1J79 (a high-permeability Permalloy), 1J85 achieves breakthrough magnetic performance through a precisely optimized composition (Ni≈80%, Mo≈5%), ultra-strict impurity control (C, S, P ≤0.01%), and multi-stage vacuum annealing — the synergistic effect of nickel and molybdenum forms a highly homogeneous austenitic structure with ultra-fine grains, minimizing magnetic domain pinning to an unprecedented degree. This alloy excels in ultra-low-frequency (1-300Hz) and ultra-weak magnetic field (≤10⁻⁹T) environments, making it the irreplaceable material for quantum sensing, ultra-high-precision medical imaging, and next-generation magnetic shielding systems.

Notably, 1J85 maintains exceptional magnetic stability over an extended temperature range (-80℃ to 150℃) and exhibits negligible magnetic property drift under mechanical stress or long-term operation, ensuring ultra-high signal-to-noise ratio (SNR) in critical magnetic circuits. Its outstanding cold workability enables the production of ultra-thin strips (down to 0.003mm) and micro-structured components, while its enhanced corrosion resistance (superior to 1J79) extends service life in harsh environments (e.g., humid, low-corrosive media). It is widely used in aerospace quantum instruments, brain-computer interface devices, ultra-high-resolution MRI systems, and quantum computing, where magnetic performance directly determines the limits of detection and precision. The following is a comprehensive breakdown of its chemical composition, physical properties, magnetic properties, and application products.

1. Chemical Composition (Mass Fraction, %)

2. Key Magnetic Properties (After Standard Heat Treatment: 1150-1200℃ primary vacuum annealing for 8-10h + 900-950℃ secondary vacuum annealing for 6-8h; furnace cooling to 400℃ at ≤10℃/h, then air cooling)

Magnetic properties of 1J85 represent the current peak of soft magnetic alloy performance, significantly surpassing 1J79 and other high-end Permalloys:

Key Notes on Magnetic Properties:

• Ultra-high Initial Permeability (μᵢ ≥150,000μ₀): 2-3 times higher than 1J79, enabling the alloy to detect ultra-weak magnetic fields down to 10⁻¹⁶T — a breakthrough for quantum sensing (e.g., dark matter detection, gravitational wave interferometers);
• Extremely Low Coercivity (Hc ≤0.8A/m): 2-3 times lower than 1J79, minimizing magnetic hysteresis loss to near-theoretical limits, ensuring ultra-low noise in magnetic circuits (e.g., SNR ≥150dB for low-noise amplifiers);
• Exceptional Permeability Stability (Δμᵢ/μᵢ ≤6%): Maintains consistent performance under long-term thermal stress and thermal shock, a critical requirement for aerospace-grade instruments with 10+ year service life;
• Ultra-low Magnetic Anisotropy (K₁ ≤150J/m³): Ensures uniform magnetic performance across the entire component, eliminating signal distortion in large-area magnetic shielding (e.g., whole-body MEG systems);
• Moderate Saturation 磁感应强度 (Bs ≥0.68T): Sufficient for ultra-precision, low-power applications (e.g., micro-sensor cores), where permeability stability and noise performance are far more critical than flux density.
• Density: Approximately 8.80g/cm³ at room temperature (25℃), slightly higher than 1J79 (8.70g/cm³) due to increased molybdenum content, but acceptable for precision components (e.g., quantum sensor cores) where performance is prioritized over weight;
• Melting Temperature Range: 1410-1460℃ (liquidus: ~1460℃; solidus: ~1410℃). The narrow melting range, combined with triple-stage vacuum refining, ensures near-zero composition segregation — critical for uniform magnetic properties across ultra-thin strips (0.003-0.01mm);
• Thermal Expansion Coefficient (CTE):

3. Physical Properties

3.1 Basic Physical Parameters

◦ 20-100℃: ~11.5×10⁻⁶/℃

◦ 20-300℃: ~12.3×10⁻⁶/℃

◦ 20-400℃: ~13.0×10⁻⁶/℃

The lowest and most gradual CTE among Permalloys minimizes thermal stress during extreme temperature fluctuations (e.g., aerospace environment -80℃ to 150℃), reducing magnetic property drift by 50% compared to 1J79;

• Thermal Conductivity (λ):

◦ 100℃: ~15.8W/(m·K)

◦ 300℃: ~18.2W/(m·K)

◦ 400℃: ~20.5W/(m·K)

Lower thermal conductivity than 1J79 reduces heat transfer between magnetic components and ultra-sensitive electronics (e.g., quantum chips), preventing thermal noise interference with precision measurements.

3.2 Mechanical Properties (After Cold Rolling + Double-Stage Vacuum Annealing)

Key Notes:

• Superior Cold Workability: The combination of ultra-high elongation (δ₅ ≥35%) and reduction of area (ψ ≥70%) enables rolling into ultra-thin strips (0.003mm, thinner than human hair) and drawing into ultra-fine wires (0.005mm) — essential for micro-electro-mechanical systems (MEMS) and chip-scale magnetic components;
• Ultra-low Hardness (HV 100-130): Easier to process into complex microstructures (e.g., multi-layered shielding films for quantum chips) than 1J79, reducing tool wear and processing costs for high-precision components;
• Stress Insensitivity: Mechanical stress (e.g., bending, assembly) causes only 5-8% permeability reduction (half of 1J79), though double-stage vacuum annealing after processing is still recommended to restore 98% of optimal magnetic performance.

4. Application Products & Industry Scenarios

4.1 Quantum Technology & Precision Sensing Field

As the only soft magnetic alloy capable of meeting quantum-level magnetic performance requirements, 1J85 is used for:

• Quantum Magnetometers: Cores of ultra-high-sensitivity SQUID (Superconducting Quantum Interference Device) magnetometers and optically pumped magnetometers (OPMs), enabling detection of magnetic fields as weak as 10⁻¹⁶T — critical for gravitational wave detection (LIGO-like projects), dark matter research, and underground resource exploration (e.g., deep mineral detection);
• Quantum Computing Components: Magnetic shielding enclosures for quantum bits (qubits) in superconducting quantum computers, blocking external magnetic interference to ≤10⁻¹²T and extending qubit coherence time to ≥100μs (a 10-fold improvement over 1J79 shielding);
• Precision Atomic Clocks: Magnetic cores in atomic clock oscillators (e.g., rubidium, cesium clocks), maintaining ultra-stable magnetic flux (Bs 0.70-0.80T) to achieve time accuracy of ≤1×10⁻¹⁶ (only 1 second error in 30 billion years).

4.2 Aerospace & Defense Field

In aerospace and defense systems requiring extreme magnetic precision and environmental robustness, 1J85 is applied to:

• Aerospace Quantum Navigation Systems: Multi-layer magnetic shielding for satellite-borne quantum inertial navigation systems (QINS), ensuring positioning accuracy of ≤0.01m/h under extreme space environments (cosmic radiation, thermal cycling -80℃ to 120℃);
• Missile Guidance Ultra-precision Sensors: Cores of magnetic gradient sensors in hypersonic missile guidance systems, leveraging ultra-low coercivity (Hc ≤0.8A/m) to detect geomagnetic anomalies with precision ≤0.1nT/m, ensuring trajectory error ≤1m over 1000km flight;
• Secure Quantum Communication: Magnetic shielding for quantum key distribution (QKD) ground stations and satellite terminals, isolating magnetic interference to ≤1nT and ensuring secure communication with bit error rate ≤10⁻¹².

4.3 Medical & Biomedical Field

In medical devices pushing the boundaries of imaging resolution and non-invasive diagnosis, 1J85 is used for:

• Ultra-high-resolution MRI Systems: Magnetic shielding for 10.5T+ ultra-high-field MRI gradient coils and radiofrequency (RF) coils, reducing external magnetic noise to ≤0.1nT and achieving tissue imaging resolution down to 50μm (enabling visualization of individual brain neurons);
• Brain-Computer Interface (BCI) Devices: Cores of non-invasive MEG (Magnetoencephalography) sensors in BCI systems, detecting weak magnetic fields from neural activity (≤10⁻¹³T) and enabling real-time communication between the brain and external devices (e.g., prosthetic limbs);
• Single-Cell Magnetic Imaging: Magnetic cores in single-cell magnetometers, detecting magnetic fields from individual cells (e.g., cancer cells labeled with magnetic nanoparticles) and enabling early cancer diagnosis with 99.9% accuracy.

4.4 High-End Electronics & Consumer Tech Field

In high-end electronics demanding ultra-low noise and chip-scale miniaturization, 1J85 is used for:

• Chip-Scale Quantum Sensors: Ultra-thin (0.003-0.005mm) magnetic shielding films for chip-scale quantum sensors (e.g., on-chip magnetometers), isolating on-chip magnetic crosstalk to ≤10⁻¹⁰T and enabling integration with CMOS (Complementary Metal-Oxide-Semiconductor) circuits;
• Ultra-Low-Noise Audio Equipment: Cores of ultra-high-end audio transformers in professional studio equipment and luxury Hi-Fi systems, minimizing hysteresis loss (P₀.₆/50 ≤0.15W/kg) and achieving SNR ≥140dB (reproducing sound with near-perfect fidelity);
• Medical Wearables: Magnetic cores in ultra-sensitive biosensors for wearable devices (e.g., non-invasive glucose monitors), detecting weak magnetic signals from biological molecules (≤10⁻¹¹T) and enabling continuous, accurate health monitoring without blood sampling.
• Smelting: Triple-stage vacuum processing is mandatory: 1. Vacuum induction melting (VIM) to control main composition; 2. Vacuum arc remelting (VAR) to refine ingot structure; 3. Electron beam melting (EBM) to eliminate trace impurities (O, N ≤0.005%) — air melting or single-stage vacuum melting is prohibited, as they cannot meet impurity control requirements;
• Cold Working:

5. Processing & Heat Treatment Recommendations

◦ Ultra-thin Strips (≤0.005mm): Multi-pass rolling with 5-10% deformation per pass, followed by intermediate vacuum annealing (850-900℃, 4h) after every 20-25% total deformation; rolling must be performed in a dust-free, low-humidity environment (≤30% RH) to avoid surface contamination;

◦ Strips/Wires (>0.005mm): Single-pass rolling/drawing with 15-25% deformation, followed by double-stage final annealing;

• Heat Treatment:

◦ Primary Annealing: 1150-1200℃ vacuum annealing (vacuum degree ≤10⁻⁵Pa) for 8-10h, furnace cooling to 600℃ at ≤10℃/h — this step eliminates residual stress and homogenizes the austenitic structure;

◦ Secondary Annealing: 900-950℃ vacuum annealing (vacuum degree ≤10⁻⁵Pa) for 6-8h, furnace cooling to 400℃ at ≤5℃/h — this step refines grains to