Ultra-small-angle X-ray scattering study of second- phase particles in heat-treated Zircaloy-4

Journal Article · Thu Jan 01 00:00:00 EST 2015 · Journal of Applied Crystallography

DOI:https://doi.org/10.1107/S1600576714024893· OSTI ID:1241393

Srirangam, Prakash; Idrees, Yasir; Ilavsky, Jan; Daymond, Mark R.

The ultra-small-angle X-ray scattering (USAXS) technique has been used to investigate and to quantify the morphology and size distribution of secondphase particles in Zircaloy-4 under various heat-treatment conditions. The alloy samples were solutionized in the phase field at 1293 K for 15 min and then cooled at different rates, including water quenching, air cooling and furnace cooling. The water-quenched samples were subsequently subjected to a thermal aging treatment at 873 K for different aging times (30, 60, 120 and 300 min). The USAXS results show that water quenching and air cooling from the phase field produces a narrow size distribution of fine-size precipitates with an average diameter of 300–800 A ° , while furnace cooling resulted in coarsening of the particles, with a broad size distribution having an average precipitate size of 600–1200 A ° . Further, the furnace-cooled sample shows a higher volume fraction of particles than the water-quenched or air-cooled sample. The USAXS results on the quenched then aged samples show that aging at 873 K for 10 min resulted in very fine size precipitates with an average diameter of 200–350 A ° . A rapid precipitation with the highest number density of second-phase particles amongst all the heat-treated samples (4.3 1020 m3) was observed in the sample aged for 10 min at 873 K. Particles of larger size and with a broad size distribution were observed in the sample aged at 873 K for 300 min. A bimodal type of particle size distribution was observed in all the heat-treated samples. Important parameters in the characterization of second-phase particles, such as the average size, size distribution, volume fraction and number density, were evaluated and quantified. These parameters are discussed for both heat-treated and aged specimens. Transmission and scanning transmission electron microscopy characterization were carried out on all heat-treated samples, to assist in interpretation and to substantiate the results from the USAXS measurements.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: National Science Foundation (NSF) - Directorate for Mathematical and Physical Sciences Division of Materials Research (MPS-DMR); Natural Sciences and Engineering Research Council of Canada (NSERC); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1241393
• Journal Information: Journal of Applied Crystallography, Vol. 48; ISSN 0021-8898
• Publisher: International Union of Crystallography
• Country of Publication: United States
• Language: English