MnAl rare-earth-free permanent magnets exhibit excellent advantages from economic and resource perspectives,which have attracted extensive attentions in recent decades.We reported the evolution in phase formation and ...MnAl rare-earth-free permanent magnets exhibit excellent advantages from economic and resource perspectives,which have attracted extensive attentions in recent decades.We reported the evolution in phase formation and intrinsic magnetic properties ofτ-phase in binary MnAl alloys with the variation in Mn:Al ratios.Ferromagneticτ-phase can be generated within the compositional range of Mn_(50+x)Al_(50-x)(x=1–8),and pureτ-phase can only be obtained in the alloys with x=4–7.With Mn:Al ratio increasing,saturation magnetization M_(s)and magnetocrystalline anisotropy constant K_(1)are gradually weakened due to the incremental antiferromagnetic Mn-1d atoms,but Curie temperature ofτ-phase is gradually increased induced by the strengthened d-d hybridization of Mn_(1a)-Mn_(1d).An attempt of doping traces of Ti was carried out in order to eliminate the negative antiferromagnetic interaction derived from Mn-1d atom.Ti atoms tend to occupy 1d sites and replace the Mn-1d atoms due to the relatively fewer valence electrons compared with Mn,resulting in the reduction in Mn_(1a)−Mn_(1d)antiferromagnetic interactions,which is demonstrated by the higher M_(s)of Mn_(55-y)Al_(45)Ti_(y)(y=1)than that of Mn_(55)Al_(45).However,with further substitution of Mn by Ti,unfavorableκ-phase is unavoidably generated.Finally,the occupation preference and the corresponding influences on local magnetic interactions as well as the magnetizations of the different alloying atoms including interstitial element C,3d atoms Ti,Co and Cu,and main-group element Ga are systematically summarized,in order to offer the guidance of designing MnAl permanent magnets with ideal magnetic properties.展开更多
基金This work was supported by the National Natural Science Foundation of China(NSFC,Grant No.52271162)the Fundamental Research Funds for the Central Universities.
文摘MnAl rare-earth-free permanent magnets exhibit excellent advantages from economic and resource perspectives,which have attracted extensive attentions in recent decades.We reported the evolution in phase formation and intrinsic magnetic properties ofτ-phase in binary MnAl alloys with the variation in Mn:Al ratios.Ferromagneticτ-phase can be generated within the compositional range of Mn_(50+x)Al_(50-x)(x=1–8),and pureτ-phase can only be obtained in the alloys with x=4–7.With Mn:Al ratio increasing,saturation magnetization M_(s)and magnetocrystalline anisotropy constant K_(1)are gradually weakened due to the incremental antiferromagnetic Mn-1d atoms,but Curie temperature ofτ-phase is gradually increased induced by the strengthened d-d hybridization of Mn_(1a)-Mn_(1d).An attempt of doping traces of Ti was carried out in order to eliminate the negative antiferromagnetic interaction derived from Mn-1d atom.Ti atoms tend to occupy 1d sites and replace the Mn-1d atoms due to the relatively fewer valence electrons compared with Mn,resulting in the reduction in Mn_(1a)−Mn_(1d)antiferromagnetic interactions,which is demonstrated by the higher M_(s)of Mn_(55-y)Al_(45)Ti_(y)(y=1)than that of Mn_(55)Al_(45).However,with further substitution of Mn by Ti,unfavorableκ-phase is unavoidably generated.Finally,the occupation preference and the corresponding influences on local magnetic interactions as well as the magnetizations of the different alloying atoms including interstitial element C,3d atoms Ti,Co and Cu,and main-group element Ga are systematically summarized,in order to offer the guidance of designing MnAl permanent magnets with ideal magnetic properties.
