Microstructural control of an Al-W aluminum matrix composite during direct laser metal deposition

JOURNAL OF ALLOYS AND COMPOUNDS

卷:813

Article

Ramakrishnan, A.¹  Dinda, G. P.¹ 

[1] Wayne State Univ, Dept Mech Engn, Detroit, MI 48202 USA

关键词: Aluminum matrix composite;    Additive manufacturing;    Tungsten (W);    Al-W intermetallics;    Microstructure control;   

DOI  :  10.1016/j.jallcom.2019.152208

来源: Elsevier

【 摘 要 】

This study focuses on the evolution of a design strategy for aluminum matrix composites (AMC) in additive manufacturing, using a mixture of 82 wt % Al and 18 wt % W (82Al-18W). Direct laser metal deposition was used to fabricate and assess the 82Al-18W AMC using three different scanning speeds (12, 6, and 1.5 mm/s). This AMC was examined by optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, calculation of phase diagrams (CALPHAD), X-ray diffraction (XRD), and microhardness measurements. The hardness of the AMC increased by 50% compared to pure aluminum. The AMC showed remarkable densification during processing with uniform distribution of fine intermetallic phases and undissolved W reinforcement in the Al matrix. A notably fine microstructure was observed within the solidified melt pool, developing phases of supersaturated solid solutions of primary alpha-Al FCC elongated cellular/doublon microstructure in the near edge of the melt pool, and fine cellular/doublon structure in the top of the solidified melt pool. The formation mechanism of the intermetallic (Al12W, Al4W, Al5W) phases during rapid solidification from the melt, and the fine eutectic structure evolving at the outer solid-liquid boundaries of the intercellular/doublon structure that is due to the presence of Ni, and Fe impurities in W is well documented. This communication reports the influence of cooling rate on the solidification structures, stable, and metastable phases observed in the 82Al-18W AMC system activating future alloy design by LMD processing. (C) 2019 Elsevier B.V. All rights reserved.

【 授权许可】

Free