Role of twinning on the omega-phase transformation and stability in zirconium. (15th February 2020)

• Record Type: Journal Article
• Authors: Arul Kumar, M.; Hilairet, N.; McCabe, R.J.; Yu, T.; Wang, Y.; Beyerlein, I.J.; Tomé, C.N.
• Is Part Of: Acta materialia. Volume 185(2020)
• Page Start: 211
• Page End: 217
• Publication Date: 2020-02-15
• Subjects: Phase transformation -- High pressure -- Zirconium -- X-ray diffraction; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2019.12.006
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: Group-IV transition metal zirconium is used in nuclear and chemical industries as a choice material for operating in extreme environments. At ambient-conditions, zirconium has a stable hexagonal-close-packed structure (α-phase), but under high-pressures it transforms into a simple-hexagonal structure (ω-phase). Experimental studies involving high-pressures have reported retention of ω-phase upon recovery to ambient-pressures, which is undesirable since the ω-phase is brittle compared to the α-phase. Understanding the α-to-ω transformation is relevant for enhancing the applicability of transition metals. In this work using in-situ synchrotron X-ray diffraction, we show that deformation twins in the α-phase lower the transformation pressure and increase the amount of retained ω-phase. Our analysis concludes that the characteristics of the stress fields associated with the twins promote the α-to-ω transformation while making the reverse transformation energetically unfavorable. This work reveals a plausible way to design Zr microstructure for high-pressure applications via controlling twinning and retained ω-phase. Graphical abstract: Image, graphical abstract