Nickel melting point (pure Ni, near 1 atm): ~1455 °C = 1728 K = 2651 °F. This value is widely accepted across authoritative references.
This temperature defines the transition from solid to liquid nickel and plays a central role in alloy development, high-temperature engineering, and advanced manufacturing technologies.
Understanding the melting point of nickel from multiple perspectives—including thermodynamics, pressure dependence, alloy behavior, and process implications—offers valuable insight into both fundamental science and industrial practice.
1. What the Melting Point Represents
The melting point is the temperature at which a material transitions from solid to liquid in equilibrium.
For pure nickel, the melting point is a sharply defined temperature—1455 °C (1728 K, 2651 °F)—since it undergoes a direct transition from crystalline solid to homogeneous liquid.
In contrast, alloys and multi-component systems generally exhibit a melting range, defined by a solidus (where melting begins) and liquidus (where the material is fully molten), due to the interaction of multiple phases and elements.
The melting point is not merely a physical constant; it has deep implications in materials science and engineering:
- Thermodynamic Reference Point: It reflects the balance between free energies of solid and liquid states, making it fundamental to phase diagrams and alloy design.
- Processing Threshold: It defines the minimum temperature required for casting, remelting, or fusion-based manufacturing methods.
- Performance Boundary: It establishes an upper limit for material applications; while nickel-based alloys can operate safely at 1000–1100 °C, they must remain below the melting point of nickel to preserve structural integrity.
In essence, the melting point represents the boundary between order and disorder in the metallic state, shaping both the scientific understanding of nickel’s behavior and its industrial utility.
2. The Science of Nickel Melting Point: Atomic Structure and Bonding
Nickel’s relatively high melting point of 1455 °C is rooted in its atomic arrangement and bonding forces.
As a transition metal, nickel crystallizes in a face-centered cubic (FCC) structure, where atoms are closely packed and share electrons through metallic bonding.
This bonding mechanism creates a “sea of delocalized electrons” that strongly binds the positively charged ions together, requiring substantial thermal energy to disrupt.
The FCC lattice also contributes to nickel’s ductility and toughness, but its stability means a significant amount of heat must be absorbed before the lattice breaks down into a liquid state.
Thus, the melting point of nickel reflects the balance between its electron configuration, metallic bonding strength,
and crystalline geometry—factors that together define its thermal resilience and industrial value.
3. Purity: The Primary Factor Shaping Nickel Melting Point
The often-cited 1455 °C melting point applies only to ultra-high-purity nickel (≥99.99%, sometimes called electrolytic nickel).
In industrial practice, nickel almost never exists in this ideal form; instead, it contains trace impurities or deliberate alloying elements that shift the melting point through the freezing-point depression effect, where foreign atoms disturb the metallic lattice and lower the transition temperature.
Impurity Effects on Melting Point
Even small concentrations of impurities can significantly influence nickel’s melting behavior:
| Impurity | Typical Concentration (%) | Melting Point Reduction (°C) | Resulting Range (°C) |
| Carbon (C) | 0.1 | 15–20 | 1435–1440 |
| Sulfur (S) | 0.05 | 8–12 | 1443–1447 |
| Iron (Fe) | 1.0 | 10–15 | 1440–1445 |
| Oxygen (O) | 0.01 | 5–8 | 1447–1450 |
For this reason, “commercially pure nickel” (such as ASTM B162 Grade 200, 99.0–99.5% Ni) generally melts over a range of 1430–1450 °C, rather than at a sharp single value.
This variation is critical for metallurgical processing: failing to account for impurity effects can lead to incomplete melting, segregation, or defects in alloy production.
Ultra-High-Purity Nickel: Critical Applications
In contrast, ultra-high-purity nickel (99.999%) adheres closely to the 1455 °C melting point.
Its stability makes it indispensable in advanced technologies where thermal precision is non-negotiable—such as semiconductor fabrication, thin-film deposition, and aerospace superalloys.
In these cases, even a few degrees of variation could compromise microstructural integrity or functional performance.
4. Nickel Alloys: How Alloying Elements Modify Melting Points
Nickel’s greatest industrial value lies not in its pure form, but in its ability to form alloys with a wide range of elements.
These alloys exhibit melting behaviors distinct from pure nickel (1455 °C), governed by atomic interactions between nickel and alloying elements.
Some elements lower the melting point through eutectic formation, while others raise or stabilize it by contributing high-melting phases.
Alloys with Lower Melting Points
Certain metals—such as copper (Cu), zinc (Zn), and manganese (Mn)—form eutectic systems with nickel.
These alloys typically melt at temperatures below both constituents, improving castability and manufacturability.
- Monel 400 (65% Ni, 34% Cu): Melting range 1300–1350 °C, about 100–150 °C lower than pure nickel.
This facilitates easier casting and forging while maintaining nickel’s corrosion resistance, making it ideal for marine valves, pumps, and chemical processing equipment. - Ni–Zn alloys: Useful in specialized corrosion-resistant coatings, benefit from lower melting points that simplify processing.
The reduced melting range enhances fluidity during solidification but may limit use in ultra-high-temperature applications.
Alloys with Higher Melting Points
When alloyed with high-melting transition metals like chromium (Cr), molybdenum (Mo), or tungsten (W), nickel forms the foundation of superalloys.
These materials may not always exceed the melting point of nickel, but they retain exceptional strength and stability at temperatures close to 80% of their melting point, a property known as creep resistance.
- Inconel 625 (59% Ni, 21.5% Cr, 9% Mo): Melting range 1290–1350 °C—lower than pure Ni,
but with vastly superior high-temperature oxidation and creep resistance. - Hastelloy X (47% Ni, 22% Cr, 18.5% Fe, 9% Mo): Melting range 1290–1355 °C, widely used in gas turbines and petrochemical reactors.
- Nickel-Tungsten Alloys (e.g., 80% Ni, 20% W): Melting point around 1600 °C,
significantly above pure nickel, employed in furnace components and wear-resistant applications.
Here the trade-off is clear: melting range alone is not the defining criterion.
Instead, alloy design balances melting behavior with mechanical stability, oxidation resistance,
and manufacturability to deliver performance far beyond what pure nickel could achieve.
5. Measurement of Nickel Melting Point: Methods and Standards
Accurate determination of melting point of nickel is critical for both industrial processing and scientific research.
Several established methods and standards ensure reproducibility and precision.
Thermal Analysis Techniques
- Differential Scanning Calorimetry (DSC): Measures heat flow as a nickel sample is heated, detecting the exact onset of melting. Ideal for high-purity nickel and small sample studies.
- Thermogravimetric Analysis (TGA): Monitors weight changes during heating; used in conjunction with DSC for purity verification and phase transition analysis.
- Drop or Furnace Melting Tests: Traditional methods involve placing a nickel sample in a high-temperature furnace and visually observing the melting point under controlled atmosphere (vacuum or inert gas). Common in industrial quality control.
Standards and Reference Guidelines
- ASTM E121: Standard test method for melting points of metals using optical or thermal techniques.
- ISO 945–1: Defines metallic structure and melting verification procedures for high-purity nickel and alloys.
- International Temperature Scales (ITS-90): Provides reference temperatures for calibration of high-precision thermocouples and furnaces.
Factors Affecting Measurement Accuracy
- Purity of the sample: Even trace impurities can shift measured melting points by 5–20 °C.
- Atmosphere control: Oxidizing environments can cause surface reactions, lowering the apparent melting point.
- Heating rate and thermal gradients: Rapid heating or uneven temperature distribution can lead to inaccurate readings; controlled ramp rates (1–10 °C/min) are recommended.
6. Why references disagree (1453–1455 °C)
You’ll see 1453 °C and 1455 °C in different handbooks. The spread reflects sample purity, impurities (O, S, C) that slightly depress the liquidus, and measurement method (DTA/DSC calibration, thermal lag).
Major data compilations converge to ~1455 °C, while industry bodies sometimes list 1453 °C; both are defensible within experimental uncertainty.
Despite these differences, 1455 °C is the widely accepted engineering value.
7. Industrial Implications of Nickel Melting Point
Nickel melting point—approximately 1455 °C for ultra-pure nickel—is more than a theoretical value; it is a critical parameter that governs every stage of nickel production and application, from extraction to high-performance component manufacturing.
Extraction and Refining
- Smelting: Nickel ores, such as pentlandite, are smelted in electric arc furnaces at 1500–1600 °C,
slightly above pure the melting point of nickel, to achieve complete liquefaction of nickel sulfides. - Electrolytic Refining: Impure nickel (95–98% purity) is refined to ultra-high-purity (99.99%+) via electrolysis.
Monitoring the melting point of intermediate nickel ensures furnace temperatures are optimized, preventing incomplete melting or unnecessary energy consumption.
Casting, Forging, and Welding
- Casting: Nickel and nickel alloys are typically cast at 50–100 °C above their melting points to maintain fluidity and minimize defects.
For example, pure nickel is cast at 1500–1555 °C, while Monel 400 (Ni-Cu alloy) melts at 1300–1350 °C, allowing lower casting temperatures while retaining corrosion resistance. - Forging: Hot forging occurs at 75–85% of the metal’s melting point (≈1100–1250 °C for nickel),
softening the metal for shaping without liquefying it, which is critical for components like turbine blades and structural frames. - Welding: Nickel-based alloys are welded using processes such as TIG or laser welding.
While arc temperatures far exceed the melting point, the heat-affected zone (HAZ) must be carefully managed to avoid local melting, cracking, or microstructural degradation.
High-Temperature Applications
- Aerospace: Nickel superalloys (e.g., Inconel 718, Inconel 625) are used in jet engine combustion chambers,
which operate at 1200–1300 °C—well below the melting range, yet requiring materials with excellent thermal stability and creep resistance. - Energy and Power Generation: Gas turbine components and nuclear-grade nickel-plated steels operate at 600–1200 °C, demanding precise thermal and mechanical properties.
- Electronics: Pure nickel is employed in thermocouples and high-temperature sensors due to its well-characterized melting point, ensuring reliable readings up to 1400 °C.
8. Quick Reference Data for Engineers
| Material / Alloy | Composition (wt%) | Melting Point (°C) | Notes / Industrial Relevance |
| Pure Nickel (Electrolytic) | Ni ≥ 99.99% | 1455 | Ultra-high-purity nickel, used in semiconductors, thin-film deposition, thermocouples |
| Commercial Pure Nickel | Ni 99–99.5% | 1430–1450 | Industrial-grade nickel for general casting and fabrication |
| Monel 400 | Ni 65, Cu 34, Others 1 | 1300–1350 | Lower melting eutectic alloy, corrosion-resistant, marine and chemical applications |
| Inconel 625 | Ni 59, Cr 21.5, Mo 9, Fe 5.5 | 1290–1350 | High-temperature superalloy for aerospace, gas turbines |
| Hastelloy X | Ni 47, Cr 22, Fe 18.5, Mo 9 | 1290–1355 | Heat- and corrosion-resistant alloy for gas turbines and chemical plants |
| Ni-W Alloy | Ni 80, W 20 | ~1600 | High-melting alloy for furnace parts, high-temperature tooling |
9. Conclusion
Nickel melting point, typically cited as 1455°C for ultra-pure nickel, is a critical parameter that influences its extraction, refining, alloying, and industrial applications.
Variations in purity, impurities, and alloying elements can significantly alter this value, creating a wide range of melting behaviors across commercial nickel grades and alloys.
Understanding these factors is essential for engineers and metallurgists to optimize casting, forging, welding, and high-temperature performance.
Moreover, nickel’s ability to form specialized alloys—ranging from lower-melting eutectics like Monel 400 to high-temperature superalloys
such as Inconel and Ni-W—extends its utility across aerospace, energy, chemical, and electronics industries.
FAQs
Does nickel melting point change with pressure?
Yes, but minimally under industrial conditions. At 1 atm (standard pressure), nickel melts at 1455°C; at 100 atm, the melting point increases by ~5°C (to ~1460°C). This effect is negligible for most applications.
Why do nickel superalloys have lower melting ranges than pure nickel but better high-temperature performance?
Superalloys (e.g., Inconel 625) contain elements like chromium and molybdenum that form stable intermetallic phases (e.g., γ’ phase) at high temperatures.
These phases prevent grain boundary sliding (creep), even if the alloy’s melting range is lower than pure nickel.
Can nickel melting point be used to identify its purity?
Yes. Measuring the melting point via DSC and comparing it to the 1455°C standard is a simple way to estimate purity.
A lower melting point indicates higher impurity content (e.g., 1430°C suggests ~0.5% total impurities).
What happens if nickel is heated above its melting point for extended periods?
Nickel will remain liquid but may oxidize in air (forming nickel oxide, NiO, which has a much higher melting point—1955°C).
In inert atmospheres (e.g., argon), liquid nickel is stable and can be held at 1500–1600°C for casting without degradation.
Are there nickel alloys with melting points above 1600°C?
Yes. Nickel-tungsten alloys (e.g., 70% Ni, 30% W) have melting points ~1650°C, while nickel-rhenium alloys (e.g., 80% Ni, 20% Re) melt at ~1700°C.
These are used in specialized high-temperature applications like rocket nozzles.
