Font Size: a A A

Martensitic Transformation And Magnetic Properties Of Ni-Mn-In Heusler Alloys

Posted on:2014-01-26Degree:MasterType:Thesis
Country:ChinaCandidate:Z Q LiaoFull Text:PDF
GTID:2231330395982807Subject:Materials science
Abstract/Summary:PDF Full Text Request
The microstructures, martensitic transformation and magnetic properties of Ni-Mn-In based alloys made by different methods have been investigated systematically by means of XRD, DSC and Versalab. The influence of atomic order degree, Co and Fe nominal substituting for Ni, and ball milling on phase constitute, phase transformation, magnetic properties are illuminated.The research found that there is a critical temperature with L21to B2structure transition for Ni50Mn35In15ribbons. The critical temperature TB2/L21is about920K. The atomic order degree of quenched ribbons decreases with increasing heat treatment temperature. The phase transformation temperatures increase with reducing atomic order degree.Co doping doesn’t form new phase for Ni50-xCoxMn35In15(x=0,1,2,3). Ni50-xCoxMn35In15ribbons consist of austenitic phase at room temperature; Co doping decreases the phase transformation temperature remarkably and enhances Curie temperature of austenitic phase. Magnetic field can decrease reverse martensitic transformation temperature. Fe doping doesn’t form new phase for Ni50-xFexMn37ln13(x=0,1,2,4) and decreases the phase transformation temperature. Ni50-xFexMn37In13ribbons consist of7M martensitic phase at room temperature.The composition of the ball milled powder is Ni47.35Mn37.71In12.43Co4.68Fe1.43. The undersize of grains will suppress phase transformation of powder after annealing. The vibration ball milled powders will occur two structure transitions with fee to disorder bcc at about382℃and bcc to L21at about654℃during annealing process. The ball milled powders are mixed phase with austenitic phase and martensitic phase after2hours annealing at800℃. Saturation magnetization of the ball milled powders increases dramatically after annealing, and it increases with annealing temperature in a range of temperature.
Keywords/Search Tags:magnetic shape memory alloy, Ni-Mn-In alloys, martensitic transformation, atomic Order degree, saturation magnetization
PDF Full Text Request
Related items