Available Alnico Magnet Grades

Magnetic and Physical Characteristics

The range of Alnico magnet alloy grades available from Dura Magnetics typically extends from 1.5 – 5.25 MGOe for sintered Alnico and 5.0 – 9.0 for cast Alnico.  This range allows for optimizing the cost, performance, and operational temperature resistance for a wide range of applications.

Sintered Alncio magnets are made with a powdered metal process.  Lower grades are isotropic, which can be magnetized in any direction, but at a loss of magnetic strength. The powder metal version of Alnico allows for easier integration of features since a tool is used and the magnet is finished to near net shape. However, sometimes the tooling cost can be a project inhibitor for small production quantities.

Cast Alnico magnets are cast in sand molds and usually require finish grinding.  Casting Alnico is the most typical manufacturing method and most cast Alncio is “orientated” and anisotropic.  This means that the magnet can only be magnetized in one direction, but this improves the magnetic strength.

Sintered Alnico – Available Grades
Dura Magnet Grade	Residual Induction Br		Coercive Force Hc		Intrinsic Coercive Force Hci		Maximum Energy Product (BH)max		Max. Operating Temp.*
	Nominal		Nominal		Minimum		Nominal		Nominal
	k-Gauss	Tesla	Oersted	kA/m	Oersted	kA/m	MGOe	kJ/m3	°C	°F
Alnico 2	7.0	0.7	500	40	540	43	1.5	12	450°C	840°F
Alnico 5	11.0	1.1	600	48	600	48	4.25	34	450°C	840°F
Alnico 8	8.8	0.88	1,530	121	1.600	127	5.25	42	450°C	840°F
* The listed maximum operating temperatures are based on an adequate Length to Diameter ratio or a properly designed magnetic circuit. The listed values are for reference and validation must occur before one chooses a design path. Please consult a Dura technical representative before selecting or designing with Alnico magnet alloy.

Cast Alnico – Available Grades
Dura Magnet Grade	Residual Induction Br		Coercive Force Hc		Intrinsic Coercive Force Hci		Maximum Energy Product (BH)max		Max. Operating Temp.*
	Nominal		Nominal		Minimum		Nominal		Nominal
	k-Gauss	Tesla	k-Oersted	kA/m	k-Oersted	kA/m	MGOe	kJ/m3	°C	°F
Alnico 5	12.2	1.22	600	48	630	50	5.0	40	500°C	930°F
Alnico 5B	12.2	1.22	650	52	660	53	5.5	44	500°C	930°F
Alnico 5 DG	12.5	1.25	690	55	700	56	6.5	52	500°C	930°F
Alnico 5-7	13.0	1.3	700	56	740	59	7.5	60	525°C	980°F
Alnico 8-HC	7.0	0.7	1,750	139	1,750	139	4.5	36	525°C	980°F
Alnico 8	8.2	0.82	1,500	119	1,600	127	5.0	40	525°C	980°F
Alnico 8B	8.8	0.88	1,500	119	1,650	131	5.5	44	525°C	980°F
Alnico 8C	9.0	0.9	1,380	110	1,440	115	7.5	60	525°C	980°F
Alnico 9	10.5	1.05	1,410	112	1,440	139	9.0	72	525°C	980°F
* The listed maximum operating temperatures are based on an adequate Length to Diameter ratio or a properly designed magnetic circuit. The listed values are for reference and validation must occur before one chooses a design path. Please consult a Dura technical representative before selecting or designing with Alnico magnet alloy.

Reversible Temperature Coefficient for Cast and Sintered Alnico
Temperature Range (°C)	Induction Br (α) (%)/°C	Intrinsic Coercivity Hci (β) (%)/°C
20°C to 150°C	-0.02 to -0.03	-0.02 to -0.03
α = Δ Br / Δ T * 100 (Br @ 20°C) [ΔT = 20°C – 150°C] β = Δ Hci / Δ T * 100 (Hci @ 20°C) [ΔT = 20°C – 150°C]

Alnico Magnets – Physical Properties
Property	Units	Value Sintered Alnico	Value Cast Alnico
Vickers Hardness	Hv	440	440-620
Density	g/cm3	6.8 – 7.0	6.9 – 7.3
Curie Temp TC	°C	810 – 860	740 – 860
Curie Temp TF	°F	1,400 – 1,580	1,460 – 1,580
Specific Resistance	μΩ⋅Cm	50- 70	45 – 75
Bending Strength	kN/mm2	0.35 – 0.76	0.05 – 0.31
Tensile Strength	kN/mm2	0.35- 0.45	0.02 – 0.15
Thermal Expansion	°C-1	+11.0 to +12.4 x10-6	+11.0 to +13.0 x10-6
The listed values are approximate and should be used as a reference. Any magnetic or physical characteristics should be substantiated before selecting a magnet material. Please engage Dura’s Design / Development team members before selecting a design path.