Peitian Wang to defend Ph.D. thesis

Peitian Wang

On March 24, Peitian Wang will defend his Ph.D. thesis, “Development of an (Fe,Sn)-based nanocrystalline soft magnetic alloy.”

Wang, who is from Jinan, China, was drawn to the field of materials science and engineering while taking a class on the fundamentals of materials science and engineering at Qingdao Technology University in his home country. After he graduated with his B.S., he came to Case Western Reserve University, where he earned his M.S. in Materials Science and Engineering in 2017.

Looking back at his time at CWRU, Wang has fond memories of attending the Intermag Conference Meeting. He particularly looked up to his advisor, Professor Matthew Willard, during his Ph.D. studies.

After he graduates in May with his Ph.D. in Materials Science and Engineering, Wang plans to return to his home country to start a career researching soft magnetic materials.

Wang’s abstract:

The D03 Fe3Sn phase shows higher magnetization and smaller magnetocrystalline anisotropy compared to Fe3Si based on the comprehensive first principles calculations. A new computation-based alloy design method, motivated by the work of Villars, was used to design a new alloy system (Fe1-x-yCoxSny)87Nb3B9Cu1 (4<x<27, 5<y<15) to achieve D03 Fe3Sn phase with the help of the melt-spinning process. Differential scanning calorimetry was used to determine the primary crystallization temperatures of the Fe79-xCoxSn8Nb3B9Cu1 alloys (x=4, 9, 14, 19 and 24), which have peak temperatures from 405℃ to 420℃ at a heating rate of 10 ℃/min. The amorphous ribbons were encapsulated in fused quartz ampoules and annealed in a tube furnace at 450°C, 500℃, or 550 ℃ for 3600seconds. X-Ray Diffraction (XRD) has been used to analyze structural properties of as-spun and heat-treated ribbons of all alloy compositions. Partial crystalline exists during the melt-spinning process for these series alloys. XRD diffractograms of the heat-treated ribbons are comprised of a B2 phase, which has a primitive cubic structure. The crystallite sizes for each heat-treated sample were estimated by Scherrer broadening to have values between 6 and 11 nm. The magnetic properties of as-spun and heat-treated ribbons were studied by vibrating sample magnetometry. Saturation magnetization and coercivity were determined from room temperature magnetic hysteresis loops. The highest magnetization value 171.4 Am2/kg was achieved by Fe60Co22Sn5Nb3B9Cu1 alloy annealed at 500℃ while the coercivity value is 67.3A/m. FeSn2 phase was observed for Fe79-xCoxSn8B9Nb3Cu1 (x=4,9, 14, 19, 24) and Fe60Co14Sn13B9Nb3Cu1 alloys after annealing at 500℃ and 550℃. A thermodynamic model was conducted to analyze the formation of the FeSn2 phase. The volume fraction of FeSn2 phase increased to ~20% at 600℃ annealing temperature. The glass forming ability of (Fe, Sn)-based alloy was improved by changing the Nb and B ratio with the decrease of the saturation magnetization values from 146.4 Am2/kg for Fe63Co14Sn8B11Nb3Cu1 alloy to 107 Am2/kg for Fe63Co14Sn8B5Nb9Cu1 alloy.