Microstructure evolution and densification behaviour of powder metallurgy Al–Cu–Mg–Si alloy

ABSTRACT

An Al–Cu–Mg–Si alloy was prepared by conventional press-sintering powder metallurgy using elemental Al powder. The phase transformation process of Al–Mg, Al–Si alloy and Cu during the sintering process was investigated in details. It was found that a series of phase transitions take place in the alloy to disrupt the oxide film of Al particle and enhance the densification process. The relative density of the sintered samples reached 98%. A new Al–Mg–Cu–O compound was found at the grain boundaries except the MgAl₂O₄ phase, it is speculated that the disruption of the oxide film was also associated with the other alloy compositions except for Mg. Furthermore, no detectable AlN compound was found at the grain boundary region although sintering with flowing nitrogen atmosphere, which is benefit from the high density of the green compact and the excellent wettability between the liquid phase and the aluminium.

KEYWORDS:

• Powder metallurgy
• solid diffusion
• liquid phase sintering
• oxide film
• AlN

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes on contributors

Tingting Qiu Master in Materials Science from the University of Science and Technology Beijing (USTB) (2019). Her master thesis is focus on the Microstructure evolution and densification behavior of powder metallurgy aluminium alloys.

Mao Wu PhD in Materials Science from the USTB (2010). Associate professor in Institute for Advanced Materials and Technology, USTB since 2014. His main research areas are metal injection moulding, metal matrix composite, microelectronic packaging technology.

Zhiyuan Du Master in Materials Science from the USTB (2019). His research field is the metal injection moulding of aluminium alloys.

Gang Chen PhD in Materials Science from the University of Auckland (2014). He has been working on the development of new materials and processes in powder metallurgy since 2007, including powder production, metal injection moulding and additive manufacturing. He has a great experience in powder metallurgy of titanium and its alloys, as well as in the characterisation and properties.

Lin Zhang professor in Institute for Advanced Materials and Technology, USTB since 2018. He graduated from South University of powder metallurgy with a master's degree; in 2005–2009, he graduated from Beijing University of science and technology with a doctoral degree; from March 2017 to April 2018, he was a visiting scholar of MIT. His research interest involves ODS alloys, refractory metal, metal 3D printing, superalloys, friction and brake materials and the other advanced powder metallurgy materials.

Xuanhui Qu professor in Institute for Advanced Materials and Technology, USTB. He is Changjiang Scholar, Jie Qing, Dean of the Institute of New Materials Technology. His research interest is special powder materials and advanced powder metallurgy technologies. He has published more than 300 SCI papers, published 5 books, and has obtained more than 100 patents. He has won 1 first prize for national teaching achievements, 1 second prize for national scientific and technological progress, 8 first prize and 10 second prizes for provincial and ministerial level scientific and technological achievements award; he also won the ‘China Youth Science and Technology Award’, ‘National Excellent Science and Technology Workers’, ‘Beijing Excellent Teacher’, ‘Baosteel Excellent Teacher Award’ and other honors.

Additional information

Funding

This work was financially supported by the National Natural Science Foundation of China [Grant Nos. 51774036, 51974029, 51574030, and 51574029].