S. Cai

Evolution of Interphase Stress in Zr-2.5%Nb during Deformation

A series of neutron diffraction in-situ uniaxial compressive deformation tests have been carried out on textured Zr-2.5Nb. Test samples were prepared from the hot rolled plate with loading axes variously parallel to each of the plate rolling (RD), transverse (TD) and normal directions (ND). The evolution of the lattice parameters in both phases were measured in all three principal directions for each case of loading axis. The average phase strains determined by Rietveld refinement showed an anisotropic yielding dependent on sample orientation relative to the parent plate. The g-phase yielded first at stresses around 330-420MPa and transfered load to the く-phase. The く-phase yielded at stresses about 400-500MPa causing reverse load transfer to the g-phase. A Finite Element Model (FEM) was used to simulate the stress strain behaviors of the phases. Despite the simplicity of this model, a very good agreement was obtained between the experimental results and the FEM calculations.

Stress-induced phase transformation in a Ti–17Nb–1Cr alloy

In situ synchrotron X-ray diffraction was used to study the deformation behavior of a Ti–17Nb–1Cr alloy at room temperature. Stress-induced martensite (SIM) transformation increased the total recoverable strain. A maximum of ∼3.5% strain recovery was obtained after proper heat treatment. Unlike other alloys with a bcc crystal structure, the β-phase has a strong (210)β texture, supporting the previous suggestion that all meta-stable β-Ti alloys may have a similar texture instead of the well-known (110)β texture after axisymmetric deformation. The ω-phase has a ()ω texture. The (041)α″ fiber texture in α″-phase was formed from the (210)β texture based on their crystal orientation relationship. Impact Statement: This manuscript reports the stress-induced phase transformation in a new β-Ti alloy with large recoverable strain and unique textures that are not widely known. GRAPHICAL ABSTRACT