Lattice parameters of martensite in Ti50.5−xNi49.5Zrx/2Hfx/2 quaternary shape memory alloys
2000; Elsevier BV; Volume: 312; Issue: 1-2 Linguagem: Inglês
10.1016/s0925-8388(00)01120-8
ISSN1873-4669
Autores Tópico(s)X-ray Diffraction in Crystallography
ResumoTi50.5−xNi49.5Zrx/2Hfx/2 (x=10–20 at.%) shape memory alloys exhibit the characteristics of B2↔B19′ one-stage martensitic transformation. The lattice parameters of B19′ martensite in these alloys are determined by XRD, SADPs of TEM and Rietveld methods. Experimental results show that lattice parameters a and c, monoclinic angle β and unit cell volume V increase, but the lattice parameter b decreases with increasing x-content in Ti50.5−xNi49.5Zrx/2Hfx/2 alloys. The results of Rietveld method indicate that the martensite of Ti50.5−xNi49.5Zrx/2Hfx/2 with x=10–20 at.% has a structure similar to that of Ti50Ni50. The parameters a, c and β of B19′ martensite in Ti50.5−xNi49.5Zrx/2Hfx/2 alloys are slightly larger, but b is slightly smaller than those in Ti50.5−xNi49.5Zrx alloys for the same x-content. The B19′ martensite of Ti30.5Ni49.5Zr10Hf10 alloy is a monoclinic structure with a=0.3068 nm, b=0.4062 nm, c=0.4882 nm and β=101.2° and has a substructure of (001)M compound twin.
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