Fracture behavior of sintered NdFeB magnets during cooling from sintering temperature

In order to explore fracture behavior of sintered NdFeB magnets during cooling from sintering temperature, in this work, we analyzed microstructure and grains distribution of the fractured samples. Because of grains irregular growth, the Nd-rich phase reunited at grain-junction region, causing internal stress concentration on grain boundary. The fracture surface showed an intergranular fracture. Cracks advanced incrementally with each stress formed at the magnet center. The propagation speed of cracks was different at different regions. Magnetic flux density decreased in the fractured section. Based on the experimental results, a fracture model has been constructed for magnets. The model can better clarify the mechanism of intergranular fracture along the grain boundaries.

[1]  S. Rehman,et al.  Improved Microstructure and Magnetic Properties of Alnico 8 Alloys by B-Doping , 2018, IEEE Transactions on Magnetics.

[2]  Musen Li,et al.  Effect of optimal aging treatment on magnetic performance and mechanical properties of sintered Nd-Fe-B permanent magnets , 2016 .

[3]  J. Q. Zhao,et al.  Effect of sintering process on the magnetic and mechanical properties of sintered Nd-Fe-B magnets , 2014 .

[4]  B. Altuncevahir,et al.  Effect of intergranular phase segregation on magnetic properties of NdFeB magnet , 2014, Electronic Materials Letters.

[5]  C. Cui,et al.  Effects of alignment on the magnetic and mechanical properties of sintered Nd–Fe–B magnets , 2013 .

[6]  S. Lee,et al.  A study on the Nd-rich phase evolution in the Nd-Fe-B sintered magnet and its mechanism during post-sintering annealing , 2012 .

[7]  S. Sugimoto,et al.  Current status and recent topics of rare-earth permanent magnets , 2011 .

[8]  Deshan Li,et al.  Grain Interface Modification and Magnetic Properties of Nd–Fe–B Sintered Magnets , 2008 .

[9]  Wei Li,et al.  Sintered Nd-Fe-B magnets with improved impact stability , 2006 .

[10]  Jin-Ming Wu,et al.  Improved magnetic properties and fracture strength of NdFeB by dehydrogenation , 2006 .

[11]  Michael H. Walmer,et al.  Microstructure and magnetic properties of sintered ndfeb magnets with improved impact toughness , 2005 .

[12]  Wei Li,et al.  Sintered Nd–Fe–B magnets with high strength , 2003 .

[13]  David Brown,et al.  Topical review Developments in the processing and properties of NdFeb-type permanent magnets , 2003 .

[14]  E. Albano,et al.  The role of interfaces in the propagation of damage in magnetic materials , 2002 .

[15]  Jian-sheng Wu,et al.  The effect of Co addition on the fracture strength of NdFeB sintered magnets , 2001 .

[16]  Jian-sheng Wu,et al.  Influence of alloying elements on mechanical properties and microstructures of sintered Nd-Fe-Co-B magnet , 2000 .

[17]  J. Wright,et al.  Fracture toughness of commercial magnets , 1996 .

[18]  K. Ohashi,et al.  High-energy NdFeB magnets and their applications , 1994 .

[19]  I. R. Harris,et al.  The magnetic and mechanical properties of NdFeB type permanent magnets and the effect of quenching , 1990 .

[20]  J. Mccall.  Understanding how components fail: Donald J. Wulpi (American Society for Metals, Metals Park, Ohio, 1985) $43.00 , 1986 .

[21]  V. Pavlov,et al.  Some characteristic cases of brittle fracture of welded constructions , 1973 .