Important Alloys of d-Block Elements
Why they form, Composition, and Applications.
By chemca Team • Updated Jan 2026
An alloy is a homogeneous mixture of a metal with other metals or non-metals. Transition metals are known for their ability to form alloys because they have similar atomic sizes (radii within 15% of each other). This allows atoms of one metal to easily replace atoms of another in the crystal lattice.
1. Why Transition Metals form Alloys?
Substitutional Solid Solutions
- Similar Atomic Radii: The atomic radii of transition metals in a series are very close to each other.
- Lattice Substitution: Atoms of one transition metal can easily take up positions in the crystal lattice of another.
- Properties: The resulting alloys are harder, have higher melting points, and are more resistant to corrosion than the parent metals.
2. Alloys of Copper
Common Copper Alloys
| Name | Composition | Properties & Uses |
|---|---|---|
| Brass | $Cu (60-80\%) + Zn (20-40\%)$ | Malleable, ductile, resistant to corrosion. Used in utensils, cartridges, condenser tubes. |
| Bronze | $Cu (75-90\%) + Sn (10-25\%)$ | Harder than copper, corrosion resistant. Used in statues, coins, medals, ship propellers. |
| German Silver | $Cu (50\%) + Zn (24\%) + Ni (24\%)$ | Contains 0% Silver. Silvery appearance. Used in utensils, resistance coils, ornaments. |
| Gun Metal | $Cu (87\%) + Sn (10\%) + Zn (3\%)$ | Very hard, resists corrosion. Used in gears, castings, bearings. |
3. Alloys of Iron (Steels)
Ferrous Alloys
Pure iron is soft. Alloying with Carbon and transition metals drastically improves properties.
| Name | Composition | Properties & Uses |
|---|---|---|
| Stainless Steel | $Fe + Cr (12-20\%) + Ni (2-10\%) + C$ | Resistant to corrosion (Rust-proof). Used in cutlery, surgical instruments, automobile parts. |
| Invar | $Fe (64\%) + Ni (36\%)$ | Very low coefficient of thermal expansion. Used in pendulums, measuring tapes. |
| Tungsten Steel | $Fe + W (14-20\%) + C$ | Extremely hard even at high temps. Used in high-speed cutting tools. |
| Manganese Steel | $Fe + Mn (10-15\%) + C$ | Very tough and resistant to wear. Used in railway tracks, rock crushers, safes. |
4. Special Purpose Alloys
1. Nichrome:
Composition: $Ni (60\%) + Cr (40\%) + Fe (\text{trace})$
Use: High electrical resistance and high melting point. Used in heating elements (toasters, irons).
Composition: $Ni (60\%) + Cr (40\%) + Fe (\text{trace})$
Use: High electrical resistance and high melting point. Used in heating elements (toasters, irons).
2. Alnico:
Composition: $Al + Ni + Co + Fe$
Use: Highly magnetic. Used to make powerful Permanent Magnets.
Composition: $Al + Ni + Co + Fe$
Use: Highly magnetic. Used to make powerful Permanent Magnets.
3. Constantan:
Composition: $Cu (60\%) + Ni (40\%)$
Use: Electrical resistance wire (Thermocouples).
Composition: $Cu (60\%) + Ni (40\%)$
Use: Electrical resistance wire (Thermocouples).
4. Amalgams:
Alloys of Mercury (Hg) with other metals (like Na, Zn, Au, Ag).
Use: Dental fillings ($Ag-Hg$), Reducing agents ($Zn-Hg, Na-Hg$). Note: Iron ($Fe$) does not form amalgam.
Alloys of Mercury (Hg) with other metals (like Na, Zn, Au, Ag).
Use: Dental fillings ($Ag-Hg$), Reducing agents ($Zn-Hg, Na-Hg$). Note: Iron ($Fe$) does not form amalgam.
5. 18-Carat Gold:
Composition: $Au (75\%) + Cu/Ag (25\%)$
Use: Jewelry (Pure 24K gold is too soft).
Composition: $Au (75\%) + Cu/Ag (25\%)$
Use: Jewelry (Pure 24K gold is too soft).
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