Thermal stability and high-temperature mechanical performance of nanostructured W–Cu–Cr–ZrC composite. (1st March 2021) - Cao, Lijun
Abstract: Improvement of high-temperature mechanical properties of W–Cu based composites is highly desirable but still a challenge. Here it is achieved by combined effects of solid solution, dispersed nano-precipitation and highly stabilized nanostructure in the W–Cu–Cr–ZrC composite, which takes advantage of the in-situ precipitated Zr–Cr–C nanoparticles and phase-separated Cr thin films. The grain size of W phase in the W–Cu–Cr–ZrC composite retained at the nanoscale up to 1000 °C (close to Cu melting point) for a long duration. The high thermal stability of the nanostructure endows the composite with a compressive strength of 1150 MPa at 900 °C, which is approximately four times as high as that of the binary coarse-grained W–Cu composite. The effects of microstructure evolution on the mechanical properties at high temperatures and its mechanisms were disclosed. The results indicated the crucial role of the microstructural stability of W phase skeleton in the overall strength of the W–Cu based composites. Graphical abstract: The thermal stability of the nanostructured W–Cu–Cr–ZrC composite was remarkably enhanced by taking advantage of cooperation between the in-situ precipitated Zr–Cr–C nanoparticles and phase-separated Cr thin films. The high thermal stability endows the composite with an outstanding compressive strength, which is approximately four times as high as that of the conventional W–Cu composites. The mechanisms were discovered for the nanostructure stabilization and effect of microstructural evolution on the high-temperature mechanical performance of the composites. Image 1 Highlights: In-situ precipitation and phase-separated film exhibit strong pinning effect. Nanostructure in W–Cu based composite was stabilized at 1000 °C. Element redistribution at high temperature leads to nanostructure instability. Strength reached 1150 MPa in nanostructured W–Cu based composite at 900 °C.