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A rolled and recrystallized commercially pure Zr sheet was β-solution treated and then cooled at two rates, i.e. air cooling (AC) and furnace cooling (FC). Microstructures and textures of original and β-cooled specimens were characterized by use of electron channeling contrast imaging, electron backscatter diffraction and X-ray diffraction techniques. Results reveal a novel phenomenon, i.e. the concurrent inheritance of microstructure and texture in the FC specimen cooled at a very slow rate. In contrast, for the AC specimen with faster cooling, typical lamellar α phases are obtained with relatively scattered texture. Based on comparatively crystallographic and thermodynamic analyses, reasons accounting for microstructure and texture differences in both cases are discussed, highlighting the significant role played by the variant selection behavior. It is postulated that increasing cooling rates should be more feasible to change the transformed texture in Zr materials.

In this paper, specimens cut from a fully recrystallized Zr702 sheet were surface-treated by pulsed laser at two different powers (200 and 50 W) and their microstructures were investigated by electron channeling contrast imaging and electron backscatter diffraction techniques. For both the laser-treated specimens, three modified zones with distinctly different microstructural features are presented from the surface to the substrate: melting zone (MZ), solid state phase transformation zone (SSPTZ) and essentially unaffected base metal zone. The MZ is completely comprised of α plates while the SSPTZ could be further divided into the SSPTZ-1 and the SSPTZ-2, according to cooling mainly from β and α + β domains, respectively. With decreasing the laser power, the modification depth and the mean width of α plates decrease. Detailed characterization on microstructural features suggests that the plate structures (MZ and SSPTZ-1) in the 200 W and the 50 W specimens are produced by diffusion and diffusionless transformation, respectively. For those untransformed α grains in the SSPTZ-2 of both specimens, in spite of maintained bulk morphologies, slight subdivisions by subgrains are found inside them due to extensive dislocation activities induced by transformation stresses and/or their recovery.

In this work, the surface of a fully recrystallized Zr702 is treated by pulsed laser following which microstructural changes are investigated by use of electron backscatter diffraction and electron channeling contrast imaging techniques. The pulsed laser treatment results in three distinctly different microstructural features from the surface to the substrate: fine α plates with a few hundred nanometers in width (zone I), irregular-shaped grains with varied sizes (zone II), and essentially unchanged equiaxed grains (zone III). The α plates result from rapid phase transformation due to easy heat extraction of the pulsed laser with dense nanoscale twins inside those plates closer to the surface. The origin of the irregular-shaped grains is found to be related to insufficient recrystallization of antecedently formed α plates near the substrate. Hardness tests reveal highest value (∼356.7 HV) near the surface in zone I and the lowest value (∼165.2 HV) in zone II. Reasons accounting for the difference are discussed in terms of various microstructural characteristics induced by the pulsed laser surface treatment.

A Cu-10Fe alloy with magnetron sputtered Al films was irradiated by high current pulsed electron beam (HCPEB) with various pulse numbers, next changes of its microstructure and corrosion property were investigated. Compared with the initial sample, microhardness and corrosion resistance of the aluminized Cu-10Fe alloys after the HCPEB treatment are remarkably improved with increasing pulse numbers. This improvement could be attributed to formation of Al2Cu intermetallic compounds, occurrence of liquid phase separation and grain refinement in the surface layer of the Cu-10Fe alloy during the process of rapid remelting and solidification induced by the HCPEB treatment.

High current pulsed electron beam (HCPEB) treatments were performed for a commercially pure Zr sheet, with remarkable surface modifications demonstrated. After the HCPEB treatments, the prior equiaxed grains with a bimodal basal texture are replaced by ultra fine plates with dense nanotwins and an unusual fiber texture of 11 2 ¯ 0 > normal to the sheet surface. Increased number of pulses leads to further refined microstructures and intensified textures, jointly resulting in continuous increase of hardness. Reasons for such modifications could mainly be attributed to ultra fast heating/cooling and strong variant selection due to presence of complex thermal and stress fields.