Tensile properties and hardness of cast Fe-Pt magnetic alloys.
BACKGROUND
There is little information about the mechanical properties of castable magnetic attachments made of iron-platinum (Fe-Pt) alloys after heat treatment.


METHODS
Dumbbell-shaped tensile specimens were cast with 5 alloys: 2 types of Fe-Pt alloys for magnets and keepers, pure Ti, Ti-6Al-7Nb, and Co-Cr alloy. The tensile specimens of the Fe-Pt magnets and keepers underwent different heat treatments to obtain the appropriate properties for a magnet and a keeper. Vickers hardness was measured prior to testing. Tensile testing was conducted in a universal testing machine at a crosshead speed of 2 mm/min until failure. Ultimate tensile strength, yield strength, elongation, and modulus of elasticity were recorded. The data were analyzed using 1-way analysis of variance and the Tukey test (alpha=.05), fractured surfaces were examined using a scanning electron microscope (SEM).


RESULTS
The highest tensile and yield strengths were found for Ti-6Al-7Nb, followed by Co-Cr, CP Ti, and the Fe-Pt keeper. There was no significant difference in ultimate tensile strength between the CP Ti and the Fe-Pt keeper. The lowest elongation was found for the Fe-Pt magnet (2.8%), whereas the Fe-Pt keeper had the highest elongation (14.0%). The Fe-Pt magnet and keeper had similar modulus of elasticity values. The hardness of the cast Fe-Pt magnets was the highest among the metals tested. SEM micrographs of the Fe-Pt keepers showed a microstructure with ductile dimple fractures, whereas the Fe-Pt magnets were characterized by brittle fractures at the grain boundaries.


CONCLUSIONS
The mechanical properties of the cast Fe-Pt keepers were similar to those of the cast pure Ti. The Fe-Pt magnets were extremely hard and brittle.
Watanabe
Ikuya
I
Department of Biomaterials Science, Baylor College of Dentistry, Texas A&M University System Health Science Center, Dallas, Texas 75246, USA. iwatanabe@bcd.tamhsc.edu
Tanaka
Yasuhiro
Y
Watanabe
Etsuko
E
Hisatsune
Kunihiro
K
D000704:Analysis of Variance; D002858:Chromium Alloys / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D004548:Elasticity; D006244:Hardness; D006801:Humans; D007501:Iron / Q000737:chemistry*; D008280:Magnetics / Q000295:instrumentation; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010984:Platinum / Q000737:chemistry*; D013499:Surface Properties; D013718:Tensile Strength; D014025:Titanium / Q000737:chemistry
D002858:Chromium Alloys; D003722:Dental Alloys; C070282:Ti-6Al-7Nb alloy; D010984:Platinum; D014025:Titanium; D007501:Iron