Zhu Jingchuan

Hydroxyapatite-Ti functionally graded biomaterial fabricated by powder metallurgy

Abstract A functionally-graded biomaterial (FGM) in a hydroxyapatite (HA)–Ti system was developed by an optimized powder metallurgical process and investigated by microstructural analysis and mechanical tests. The constituents in sintered HA–Ti FGM distribute gradually with the variation in chemical composition, eliminating the macroscopic interfaces, such as that in HA–Ti direct joint. Partial decomposition of HA phase was found in interlayers of the FGM due to the co-existence of Ti during sintering. Mechanical properties in HA–Ti FGM also exhibit gradient distributions. Vickers hardness and Young’s modulus are strongly affected by the porosity. However, bending strength and fracture toughness increase remarkably with the rise of Ti content, especially in the Ti-rich region. Maximum strength and toughness (971.96 Mpa and 29.691 MPam 1/2 respectively) were reached in the pure Ti layer, which are far higher than those of human bone. In addition, the strengthening and toughening mechanism was discussed. In summary, HA–Ti FGM is a promising biomaterial for use as a hard-tissue replacement implant, considering its mechanical behaviors.

Fabrication and microstructure of ZrO2/NiCrCoAlY graded coating by plasma spraying

Abstract An 8 wt% Y2O3-ZrO2/NiCrCoAlY graded coating was fabricated on a TC4 (Ti-6Al-4V) surface by air plasma spraying. Microscopic analysis showed that the ZrO2/NiCrCoAlY graded coating exhibits a stepwise distribution in composition from metallic bond layer to ceramic top layer, consisting of t′-ZrO2 phase and supersaturated Ni-based solid solution phase, and displays tight coherence with the TC4 substrate. In addition to mechanical combination, chemicometallurgical reaction combination occurs at some locations and small amounts of NiTi2 and TiAl3 phases at the coating-substrate interface develop during spraying.

First-Principles Study on Elastic Properties and Electronic Structures of Ti-Based Binary and Ternary Shape Memory Alloys

The elastic properties and electronic structure of B2 phase binary TiM (M = Fe, Co, Ni, Pd, Pt and Au) and ternary Ti50Ni43.75Pd6.25, Ti50Ni43.75Cu6.25 shape memory alloys are studied by the plane-wave psedudopotential method within the local density approximation. The elastic constants and density of states are calculated. Our calculations show that the martensitic transformation behaviour of these alloys is closely related to their elastic properties. The Ti d DOS at the Fermi level is mainly responsible for the B2 phase stability of these alloys.

Mechanical Properties and Microstructure of in-situ TiCp Reinforced Aluminum Base FGM by Centrifugal Cast

ABSTRACT The TiCp/2020Al FGM was fabricated by in-situ reaction in melted Al alloy and the following centrifugal cast, and was investigated by means of microscopy observation and mechanical property test. The hardness and bending strength of the FGM gradully varied corresponding to the composition gradient, and the wear resistance was remarkably improved due to the formation of TiCp-rich surface layer that is strongly bonding with 2024A1 substrate through the TiCp/2024Al graded interlayer.