LOGOSoft and Hard Magnetic MaterialsClassification of Magnetic MaterialsvSoft Magnetic MaterialsvHard Magnetic MaterialsvInformation Magnetic MaterialsvSpecial Function Magnetic MaterialsSoft Magnetic MaterialsSoft magnetic materials are mainly referred to those easily magnetized repeatedly and easily demagnetized after removal of the external magnetic field. Definition:v The area within a loop represents a magnetic energy loss per unit volume of material per magnetizationdemagnetization cycle. v The relative area within the hysteresis loop is small; it is characteristically thin and narrow. Fig. 18.16 Schematic magnetization curves for Soft magnetic materials Soft Magnetic MaterialsSoft Magnetic Materialsl high initial permeability (i) l high maximum permeability (max) l low coercivity (Hc) l high saturation magnetization (Ms) l low remanence (Br) l high resistivity l low hysteresis energy loss; Features:www.themegallery.com Soft Magnetic MaterialsComposition Structural VariablesStructural Defects InfluenceInfluence factorsfactorssaturation magnetizationsusceptibility; coercivity (Hc)domain walls; coercivity (Hc)hysteresis energy lossElectrical Resistivitywww.themegallery.com Soft Magnetic MaterialsClassificationClassificationmetal soft magnetic materialsferrite soft magnetic materialsnano-crystalline soft magnetic materialspure iron; iron-silicon alloys; iron-nickel alloys; permalloy；MnZn; NiZn; MgZn; Co2Y; Co2Z; amorphous; nano-crystalline； Soft Magnetic Materialswww.themegallery.com Soft Magnetic Materialsmagnetic amplifier;pulse transformerApplications generators; motors; dynamos; switching circuitsenhance by an appropriate heat treatmentHard Magnetic MaterialsHard magnetic materials are those have a high resistance to magnetization, and still retain a high residual magnetization after removal of the external magnetic field, also known as permanent magnet materials.Definition:Hard Magnetic Materialsv The area within the hysteresis loop of hard magnetic materials is big; it is characteristically wide. v This energy product (BH)max corresponds to the area of the largest B-H rectangle that can be constructed within the second quadrant of the hysteresis curve.Fig. 18.17 Schematic magnetization curves for Hard magnetic materials v The hysteresis characteristics for soft and hard magnetic materials are compared in Figure 18.18. v From the figure, we can see the difference between these two materials in terms of magnetization more clearly.Fig. 18.18 Schematic magnetization curves for Soft and Hard magnetic materials Hard Magnetic Materialsl high coercivity (Hc) l high remanence (Br) l low initial permeability (i) l high energy product (BH)max l high hysteresis energy loss l high saturation flux density l stability; Features:www.themegallery.com Hard Magnetic Materialsmicrostructure of material domain wall motionexternal fieldInfluenceInfluence factorsfactorscoercivity (Hc); susceptibilitywww.themegallery.com Hard Magnetic MaterialsClassificationClassificationmetal hard magnetic materialsferrite hard magnetic materialslanthanon hard magnetic materialsmagnet steels; Cu-Ni-Fe alloys, Al-Ni-Co alloys； BaO-6Fe2O3; SrO-6Fe2O3; SmCo5; Nd2Fe14B； High-energyConventional by the value of (BH)max Hard Magnetic Materialswww.themegallery.com Hard Magnetic Materialsmotors; clocks;cordless drills; screw drivers; automobiles; audio and video recorders; Applications speakers in audio Systems; lightweight earphones; hearing aids; computer peripherals;LOGO