High-strength and tunable plasticity in sputtered Al–Cr alloys with multistage phase transformations. (February 2021)

• Record Type: Journal Article
• Authors: Li, Qiang; Shang, Zhongxia; Sun, Xing; Fan, Cuncai; Su, Ruizhe; Richter, Nicholas A.; Fan, Zhe; Zhang, Yifan; Xue, Sichuang; Wang, Haiyan; Zhang, Xinghang
• Is Part Of: International journal of plasticity. Volume 137(2021)
• Publication Date: 2021-02
• Subjects: High strength -- Plasticity -- In-situ micromechanical testing -- Phase transformation -- Amorphous; Plasticity -- Periodicals; Plasticité -- Périodiques; Plasticity; Periodicals; 620.11233
• DOI: 10.1016/j.ijplas.2020.102915
• Languages: English
• ISSNs: 0749-6419

Abstract

Abstract: To raise mechanical strength of metallic materials, methods such as grain refinement and amorphization are usually utilized but sacrifice plasticity. Strength and plasticity are largely dictated by dislocation-defect interactions in crystalline materials and by shear banding in metallic glasses, depending significantly on the length scales of microstructural features. Here we report on the evolution of microstructures and multistage phase transformations from micro/nanocrystalline to an entirely amorphous structure, realized by tailoring the composition of Cr in co-sputtered Al1 00 -x Crx (x = 0–25 at%) alloys. The associated Cr segregation caused the formations of different dual-phase nanocomposites. In-situ micromechanical experiments revealed that the flow stress of Al–Cr alloys can reach 2.4 GPa and the deformation behaviors varied drastically with Cr composition. This study established the mechanistic connection between the Cr composition-dependent evolution of microstructure and ultrahigh strength as well as plasticity, and revealed the benefits of building nanocomposites through a multistage phase transformation to improve the plasticity of nanocrystalline and amorphous materials. Highlights: Cr segregates at grain boundaries in Al–Cr alloys with a wide compositional range. The segregation enables multistage phase transformation: FCC-Al7 Cr-amorphous. Microstructure-dependent flow stress could reach 2.4 GPa for Al alloys. Nanocomposites could improve plasticity of nanocrystalline and amorphous materials. Mechanistic connection between property and microstructure is established.