An X-ray diffraction study of the δ → α′ transformation in a Pu-2 at% Al alloy

• Published in: Journal of nuclear materials 1983, Vol.115 (1), p.63-68
• Main Authors: Zukas, E.G., Hecker, S.S., Pereyra, R.A.
• Format: Article
• Language: English
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/0022-3115(83)90343-4

The face-centered cubic (fcc) δ phase of plutonium is stable from 310° to 458°C. An addition of 2.0 at% aluminum retains the δ phase metastably to room temperature. This δ phase transforms to α′ during subzero thermal treatments. Under hydrostatic compression at room temperature, the δ transforms initially to β′, and this then transforms to α′ at the higher pressures. During mechanical polishing, the δ phase transforms to α′. An X-ray diffraction study of this transformed zone by sequential removal of thin surface layers by electropolishing shows that this transformation is not directly from δ to α′, but from δ to γ with the γ phase then transforming to α′. There is no evidence for the presence of either the β or β′ phases when the δ phase is transformed by mechanical polishing.