Qingshan Cai

Microstructure and properties of Ti/Al lightweight graded material by direct laser deposition

ABSTRACT A novel Ti/Al lightweight graded material was fabricated successfully using the direct laser deposition process, with the composition continuously changing from 100 vol.-% Ti6Al4V to 100 vol.-% AlSi10Mg. Microstructures and phase transformations were characterised, and the mechanical properties of the Ti/Al lightweight graded material were investigated. It was found that element concentrations followed a nearly linear relationship along the compositional gradient. The maximum hardness reached 619 HV in the ‘II’ zones, and then it decreased gradually to 214 HV at the outermost layer, with the increase in the proportion of AlSi10Mg. The values for the ultimate tensile strength were above 400 MPa, and the fracture surfaces indicated a transition from ductile to brittle fracture along the graded direction.

New method for preparing micron porous aluminium via powder metallurgy

ABSTRACT In this work, micron porous aluminium (Al) specimens with various porosities were successfully prepared via a cold pressing-vacuum sintering-dissolution process (SDP) with water-soluble granules as space holders. Effects of the parameters of the sintering process on microstructure, density, and hardness were investigated. Results show that SDP was used to synthesise open-cell porous aluminium with uniform holes and enabled easy control of the microstructure porosity of porous aluminium. We also found that vacuum sintering and the addition of magnesium (Mg) improved the sintered behaviours. Based on our findings, the optimised sintering parameters (temperature and time) for porous aluminium are 650°C and 270 min, respectively.