The North American P/M industry has enjoyed seven years of steady growth with metal powder shipments reaching 511,185st (464,053mt). Growth markets include iron and steel, stainless steel, alaminum, copper and tool steel powders. The auto market continues to dominate the conventional P/M parts industry. Hot isostatic pressing, metal injection molding and powder forging are also growing. The need for global P/M materials standards is becoming increasingly important.

Sintered aluminum alloys are an attractive material for the automobile industry, both because of the low specific gravity and high strength-to-weight ratio of aluminum itself, and the fabrication advantages associated with a powder metallurgy process. However, properties such as impact, stiffness, corrosion and wear resistance are often poor, thereby restricting the widespread use of these materials. Recent work by the authors has shown that hardness, wear resistance and tensile properties of a P/M Al–Cu–Mg ternary master alloy can be improved using a novel diffusion/supersolidus liquid phase sintering process. Improvements were due to in-situ microalloying during sintering, in particular, the influence of Ag and Sn. To complement this work, the present investigation addresses the response of a commercial alloy, AA2014, to the microalloying process. Results show that sintered densities for the commercial alloy were relatively unaffected by the presence of either Ag or Sn, and were superior to the ternary master alloy. Hardness and tensile properties were also improved relative to those obtained for the ternary, and were comparable to wrought 2014. Examination of final microstructure of Ag modified AA2014 using TEM showed the presence of Ω as the principal precipitate, but only after extended sintering times. This particular precipitate is believed to contribute to enhanced hardness. The apparent absence of Ω for short sintering times was due to the presence of silicon in the commercial product. However, the corrosion behavior of the P/M AA2014 was superior to the wrought product and thus the process is presented as a potential P/M alternative to using ingot metallurgy techniques for microalloying.

State-of-the-P/M industry in North America : 1999

On enhancing the mechanical properties of aluminum P/M alloys

The conventional press-and-sinter powder metallurgy (P/M) technique is a unique cost-effective method for net shape or near net shape fabrication of complex aluminium parts. The chapter begins by providing a historical account of aluminium P/M and its application in North America, where the industry originated. It then reviews key issues of the press-and-sinter aluminium P/M technique and the science of sintering aluminium and its alloys under nitrogen, including the distinctive roles of magnesium and tin.

Sintering of aluminium and its alloys

Enhancement of liquid phase sintering through Al–Si additions to Al–Cu systems

Complex aluminium alloy components fabricated by powder metallurgy (P/M) offer the promise of a low cost and high strength-to-weight ratio, which meets the demands of the automotive sector. This paper describes the die compaction and sintering response of an atomised Al-6061 alloy powder containing Mg and Si produced by rapid solidification. A design of experiments is used involving three levels for each of the die compaction pressure, sintering temperature, peak temperature hold time and heating rate. Three trials were used to obtain the optimum press sinter processing conditions. Besides the mechanical properties, phase transformation and microstructure are investigated. Supplemental insight is gained through thermogravimetric analysis, differential scanning calorimetry and SEM with energy dispersive spectroscopy. Analysis of variation is used to quantify the contribution of each design variable to the mechanical properties.

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State-of-the-P/M industry in North America : 1999

Citations

On enhancing the mechanical properties of aluminum P/M alloys

Sintering of aluminium and its alloys

Enhancement of liquid phase sintering through Al–Si additions to Al–Cu systems

Sintering behaviour of Al-6061 powder produced by rapid solidification process

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