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Influence Of Rare Earth Gd Addition On The Martensitic And Magnetic Transformation Behaviors Of Ni-mn-in Metamagnetic Shape Memory Alloys

Posted on:2011-08-02Degree:MasterType:Thesis
Country:ChinaCandidate:L N BaiFull Text:PDF
GTID:2191360305454188Subject:Materials Processing Engineering
Abstract/Summary:PDF Full Text Request
Ni50Mn34.5In15.5-xGd x,Ni50Mn35In15-xGd(xx=0.1,0.5,1,2)alloys were melting by vacuum arc furnace under. And the melting of the alloy after 900℃×24h of the diffusion annealing quenched to 900℃×2h in ice water. The martensitic and magnetic behaviors of the alloys were investigated by DSC,VSM,X-ray diffraction and Metallographic microscope etc. The experi -mental alloy phase transformation and magnetic properties were studied.Experimental results show that rare earth element Gd on the magnetic drive NiMnIn shape memory alloy transformation temperature have a more significant effect on. It can be greatly improved martensitic transformation temperature and alloy composition on the martensite transition temperature also has an influence. When the alloy in the amount of other elements remain unchanged, changes in the content of In, when martensitic transformation temperature Ms, Mf, As, Af are increasing with the In content decreases ; Electron concentration in the 7.88-7.97 range, due to join the rare-earth alloy Gd makes the electronic concentration, martensitic phase transfor -mation temperatures rise.By analyzing the X-ray diffraction pattern of the test alloys we found the parent organization for the phase mixture of austenite and martensite at room temperature parent phase for the L21 body-centered cubic structure. Plus the shape memory alloy of rare earth Gd the main indicator of the location of diffraction peaks remain basically unchanged, including (220),(222),(400),(332), indicating that additions of rare earth Gd may not change the structure of alloys is still austenite and martensite of the hybrid organization. But it created a new diffraction peaks, such as the monoclinic martensite landmark 10M diffraction peaks (0010), (0210), (323) and so on. When the amount of Gd join to 0.5,1,2 at% , X-ray diffraction patterns of (220) diffraction peaks clearly split, indicating a new phase formation.When NiMnIn alloys add rare earth elements Gd , the alloy grain size and martensite lath has been significantly refined. Adding too many rare earth Gd would precipitate a new phase grain boundary. Ni50Mn34.5In15.5-xGd x and Ni50Mn35In15-xGdx series alloys are mainly directed form of martensite and lath-shaped. Ni50Mn35In14Gd 1 and Ni50Mn34.5In14.5Gd 1 alloys with a single variant of martensite appears to form a lath martensiteGd impacts magnetic alloys NiMnIn series of , especially the Hc and Mr, two groups of alloy measured results are basically the same. Ni50Mn35In14.5Gd0.5 and Ni50Mn34.5In15Gd0.5 highest coercivity alloys, while the other alloys the coercivity increase is not obvious. Ni50Mn35In15-xGdx series of alloys with the residual magnetic flux density Mr of rare earth Gd addition amount increased with the increase.
Keywords/Search Tags:rare earth Gd, single martensite variants, refine, shape memory effect
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