Physical Properties
Untitled Document

Magnesium is used in both its pure form and as an alloy. Depending on the composition of the metal, there can be notable differences in many physical properties. The data below is primarily regarding pure magnesium however several common alloys are also included in the data and will be noted accordingly.


About the Element Magnesium

  • Silvery, white metal
  • Symbolized by Mg on periodic table
  • Atomic #12
  • Atomic weight of 24.305
  • Atomic radius of 0.160 nm (6.3x10-9in)
  • Part of the s-block and group 2A (alkaline earth metals)
  • Has two valance electrons
  • Has 3 natural isotopes with mass numbers 24,25 and 26
  • Has a hexagonal close packed (HCP) crystal structure in pure form
  • Standard state is solid at a temperature of 298K
  • At a density of 1.7g/cm3(106.13lb/ft3) at 20°C (68°F), it is the least dense of structural metals


Thermal Properties

Boiling Point: 1107±10°C (2024.6±50°F)

Enthalpy:

T (°C)
T (°F)
Enthalpy (kJ/kg)
Enthalpy (BTU/lb)
127 260.6 107 46.0
227 440.6 218 93.7
427 800.6 454 195.2
627 1160.6 709 304.8
727 1340.6 1202 516.8
1127 2060.6 7287 3132.8
1727 3140.6 7800 3353.4
2727 4940.6 8656 3721.4


Entropy:

T (°C)
T (°F)
Entropy (kJ/kg•K)
Entropy (BTU/lb•F°)
20 68 1.34 .320
127 260.6 1.65 .394
327 620.6 2.11 .504
527 980.6 2.46 .588
727 1340.6 3.15 .752
927 1700.6 3.41 .814
1027 1880.6 3.52 .840
1127 2060.6 7.62 1.82
1727 3140.6 7.93 1.89
2727 4940.6 8.27 1.98


Heat of Combustion: 25.1 MJ/kg (10,791.06 BTU/lb)

Heat of Fusion: The specific heat of fusion if only slightly affected by alloying meaning that the values for alloys and pure magnesium are close. The heat of fusion for pure magnesium is 0.370± 0.015 MJ/kg (159.07±±6.45 BTU/lb).

Heat of Vaporization:

T (°C)
T (°F)
Heat of Vaporization
Boiling Point Boiling Point 5.26-5.65
438 820.4 5.69
829 1524.2 5.51


MeltingPoint/Range:

Alloy
T (°C)
T (°F)
Pure Magnesium 650 1202
AZ91D 470-595 875-1105
AZ81 490-610 915-1130
AM20 618-643 1145-1190
AM50A 543-620 1010-1150
AM60B 540-615 1005-1140
AE42 565-620 1050-1150
AE42 565-620 1050-1150


Specific Heat:

T (°C)
T (°F)
Specific Heat (kJ/kg•K)
Specific Heat (BTU/lb•°F)
-253 -423.4 .015 .004
27 80.6 .914 .218
127 260.6 1.026-1.084 .245-.259
327 620.6 1.178 .281
527 980.6 1.277-1.278 .305
649 (solid) 1200.2 (solid) 1.361 .325
650 (liquid) 1202 (liquid) 1.323 .316
727 1340.6 1.357-1.358 .324
827 1520.6 1.402-1.403 .335
1127-2727 (gas) 2060.6-4940.6 (gas) 8.563 2.045


Thermal Conductivity: The thermal conductivity of magnesium is slightly affected by temperature variations. Alloying has a great effect on thermal conductivity. The thermal conductivity values are calculated from electrical conductivity values.

Pure Magnesium:

T (°C)
T (°F)
Thermal Conductivity (W/m•K)
Thermal Conductivity (BTU/hr•ft•°F)
-173 -279.4 169 97.65
0 32 157 90.71
20 68 147-168 84.94-97.07
25 77 156 90.14
50 122 149 86.09
100 212 148 85.51
200 392 146-163 84.36-94.18
300 572 145 83.78
400 752 130-143 75.11-82.62


Linear Thermal Expansion Coefficient: Alloying only has a minimal effect on the coefficient value.

T (°C)
T (°F)
Specific Heat (kJ/kg•K)
0-160 32-320 27.3
20-100 68-212 26.0-26.1
20-200 68-392 27.0-27.1
20-300 68-572 27-28
20-400 68-752 28.9
20-500 68-932 29


Solidification Shrinkage: The amount of shrinkage that occurs when pure magnesium goes from liquid to solid, relative to the volume of the liquid metal, is 2.96-4.20 percent liquid volume.


Electrical Properties

Electrical Conductivity:

Alloy
Conductivity at 20°C (68°F) (MS/m)
AZ31 10
  18.5% IACS
AZ61 8.28
  11.6% IACS
AZ63 15% IACS
AZ81 7.3
  12% IACS
AZ91 7.1
  10.1% IACS
AZ8 7.5
AZ41 9.7


Electrical Resistivity:

Alloys at 100°C (212°F)
Electrical Resistivity (nΩ•m)
Electrical Resistivity (nΩ•in)
AM20 89 3503.9
AE42 98 3858.3
AS21 104 4094.5
AM50 122 4803.1
AZ91 163 6417.3
Pure Magnesium 60 2362.0


Pure Magnesium at Varying Temperatures:

T (°C)
T (°F)
Electrical Resistivity (nΩ•m)
SElectrical Resistivity (nΩ•in)
20 68 44-45 1732.3-1771.7
50 122 50.1 1972.4
100 (Extruded) 212 (Extruded) 58.5 2303.1
100 212 56 2204.7
300 (Extruded) 572 (Extruded) 93 3661.4
300 572 95 3740.2
400 (Extruded) 752 (Extruded) 121 4763.8
600 1112 170 6692.9
649 (solid) 1200.2 (solid) 154 606
650-900 (liquid) 1202-1652 (liquid) 274-288 10787-11339


Other Properties

Sound Velocity: In pure magnesium at room temperature – 4602-4800m/s (15,098.43-15,748.03 ft/s)

Surface Tension: In pure magnesium, it is linear inside the temperature range of 681-894°C (1257.8-1641.2°F). When the elements Li, Ca, Sb, Sr, Pb, Ba, or Bi are added, surface tension is reduced. For solid magnesium, surface tension close to -273°C (-459.4°F) is 1.447N/m (.099lb/ft) and at 25°C (77°F) it is 0.190N/m (.013lb/ft).

Values for Liquid Magnesium:

T (°C)
T (°F)
Pressure (kPa)
Pressure (lb/in2)
650 1202 .570 .039
650 1202 .556 .038
681 1257.8 .563 .039
700 1292 .542 .037
700 1382 .550 ± .15 .038 ± .010
750 1382 .526 .036
894 1641.2 .502 .034


Vapor Pressure for Pure, Liquid Magnesium:

T (°C)
T (°F)
Tension (N/m)
Tension (lb/ft)
620 1148 .13 .019
727 1340.6 1.1 .160
827 1520.6 4.5 .652
877 1610.6 8.8 1.28
900 1652 13 1.89
1027 1880.6 51 7.40
1190 2174 203 29.44
1330 2426 507 73.53


Dynamic Viscosity:

T (°C)
T (°F)
Viscosity (mPa•s)
Viscosity ((lb/ft•s)•104)
652 1205.6 1.236, 1.228 8.30606, 8.252
658 1216.4 1.213, 1.199 8.151, 7.519
672 1241.6 1.147, 1.119 7.708, 7.519
683 1261.4 1.107, 1.069 7.439, 7.183
703 1297.4 1.035, 0.983 6.955, 6.605
725 1337 0.963, 0.900 6.471, 6.048

International Magnesium Association
1000 Westgate Drive, Suite 252  |  Saint Paul, Minnesota 55114 USA
P: +1 651.379.7305  |  F: +1 651.290.2266  |  E: info@intlmag.org
Copyright ©2016

Member Login