The Ti50-0.5xNi50-0.5xZrx series alloys were prepared by vacuum arc melting and subsequent suction casting. Metallographic observation and tensile mechanical tests show that adding trace amount of Zr can reduce grain size and increase higher tensile strength and elongation,however,excessive Zr content can easily lead to the formation of brittle intermetallic compound Zr2Ni and reduce its mechanical properties. The multi-pass cold-rolling deformation and annealing treatment on Ti49.9Ni49.9Zr0.2 alloy were carried out. The results show that the tensile strength σb and the elongation δ of the Ti50-0.5xNi50-0.5xZrx alloys increase with the increase of cold-rolling deformation. Compared with the unrolled alloys,after four-passes cold-rolling deformation,the tensile strength and the elongation after fracture of the alloys increase from 561 MPa,1.14％ to 768 MPa,35.1％,respectively.Microscopic observation of SEM and TEM show that the hard Ti2Ni particles distributed along the grain boundaries during the cold rolling process are sheared and broken,resulting in a discontinuous distribution of refinement. After 700 ℃ annealing process,the deformed microstructure has recovery recrystallization,resulting in the appearance of nanocrystalline and amorphous regions. Moreover,a large number of plate-like nano-twin structures and high-density dislocations appear in the TiNi matrix with the increase of cold-rolling deformation.
关键词
TiNi合金/力学性能/冷轧形变/微观结构/Zr元素添加
Key words
TiNi alloy/mechanical property/cold-rolling deformation/microstructure/Zr-element addition
维普
万方数据