Tungsten-nickel alloy, also known as tungsten heavy alloy, usually consists of tungsten and nickel-iron or nickel-copper matrix. This alloy has several important properties, including:

1. High density: Tungsten-nickel alloy has high density, allowing it to be used in applications where weight is a critical factor, such as the aerospace and defense industries.

2. High strength: The alloy has high tensile strength and good mechanical properties, making it suitable for use in heavy-duty applications.

3. Good machinability: Tungsten-nickel alloy can be machined into various shapes and complex parts can be produced.

4. Thermal and electrical conductivity: The alloy has good thermal and electrical conductivity, making it suitable for certain electrical and electronic applications.

5. Corrosion resistance: Tungsten-nickel alloy is corrosion-resistant and suitable for use in harsh environments.

These properties make tungsten-nickel alloys valuable in a wide range of applications including the aerospace, automotive, military and medical industries.

Due to its unique properties, humans use tungsten for a variety of applications. Some common uses for tungsten include:

1. Filament in light bulbs: Tungsten is used to make the filament in incandescent light bulbs due to its high melting point and heat resistance.

2. Electrical contacts and electrodes: Tungsten is used in electrical contacts and electrodes due to its high melting point and excellent electrical conductivity.

3. Industrial machinery and tools: Tungsten is used in the production of cutting tools, drill bits and other industrial machinery due to its hardness and wear resistance.

4. Aerospace and Defense Applications: Due to its high density and strength, tungsten is used in the aerospace and defense industry for applications such as high-speed cutting tools, armor-piercing ammunition, and counterweights.

5. Medical devices: Due to its high density and strong ability to absorb radiation, tungsten is used in medical devices such as radiation shielding and collimators.

These are just a few examples of the many applications of tungsten in various industries.