The production of Al-transition metal alloys by laser alloying requires the treatment to be carried out at low scanning speeds in order to dissolve the high melting point addition elements. This procedure results in alloys containing a significant number of defects and large primary intermetallic compound particles that reduce the treatment’s usefulness. To overcome this problem a two-step laser processing technique was developed, consisting of a preparatory step, using long interaction times, followed by a structure-refinement step, using short interaction times. This concept was tested in the production of Al-(3.5-8.6 wt.%)Mo surface alloys with improved strength. The alloys were prepared by alloying Mo powder into Al using a CO2 laser and an interaction time τ=0.26 s. Their structure is formed of coarse needle-shaped and equiaxed (cubic, rectangular, etc.) particles of Al5Mo intermetallic compound dispersed in a cellular-dendritic matrix of α-Al. Remelting was performed using 0.03<τ<0.26 s. In the remelted layers the same intermetallic compounds were found, but most particles are composite and present a radial morphology. Growth of these particles often occurred on primary equiaxed or needle-like particles that did not dissolve during remelting. The volume fraction of intermetallic compounds increases with the remelting speed, resulting in surface layers with increasing hardnesses, up to 350 HV.
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ICALEO '96: Proceedings of the Laser Materials Processing Conference
October 14–17, 1996
Detroit, Michigan, USA
ISBN:
978-0-912035-54-3
PROCEEDINGS PAPER
Laser alloying: A tool to produce improved Al-Mo surface alloys Available to Purchase
A. Almeida;
A. Almeida
Departamento de Engenharia de Materials, Instituto Superior Técnico
Av. Rovisco Pais, 1096 Lisboa, Portugal
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R. Vilar
R. Vilar
Departamento de Engenharia de Materials, Instituto Superior Técnico
Av. Rovisco Pais, 1096 Lisboa, Portugal
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Published Online:
October 01 1996
Citation
A. Almeida, R. Vilar; October 14–17, 1996. "Laser alloying: A tool to produce improved Al-Mo surface alloys." Proceedings of the ICALEO '96: Proceedings of the Laser Materials Processing Conference. ICALEO '96: Proceedings of the Laser Materials Processing Conference. Detroit, Michigan, USA. (pp. pp. A123-A132). ASME. https://doi.org/10.2351/1.5058993
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