Banca de QUALIFICAÇÃO: MÚCIO DANTAS DE MEDEIROS

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : MÚCIO DANTAS DE MEDEIROS
DATE: 03/11/2020
TIME: 13:00
LOCAL: VIRTUAL
TITLE:

Study of directional solidification of Zn-8wt.%Al-xCu alloys

KEY WORDS:

solidification; Zn-Al-Cu alloys; thermal parameters; microstructure; hardness.

PAGES: 79
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUMMARY:

Zinc is one of the most non-ferrous metals produced after aluminum and copper, being the most used in functional and decorative applications. The main advance in the foundry industry for zinc-based alloys in recent years has been in the development of new zinc-aluminum alloys. However, Zn-Al alloys have a low lubrication level, low ductility at room temperature and reduced mechanical strength  at high temperature. In this sense, this work aims to study the effects of copper (Cu) additions on the microstructure, on the thermal parameters such as growth rate (V_L) and cooling rate (Ṫ_L), and on the hardness of the hypereutectic Zn-8wt.% Al alloy. Techniques such as X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Optical Microscopy (OM) and Scanning Electronics (SEM) were used to characterize the as-cast samples.  The results showed that Zn-Al-Cu alloys are formed by an eutectic matrix [(Zn)+(Al+Zn)] with lamellar and fibrous morphology also containing τ'-Al₄Cu₃Zn intermetallic particles and Al-rich pro-eutectic dendrites (Al'), with alternating lamellae of Al and Zn, from the eutectoid transformation [(Al')↔(Al)+ (Zn)]. Note that Cu additions did not promote morphological changes in the eutectic, being dispersed both in the eutectic regions in solid solution and in the  τ’-Al₄C_u3Zn intermetallics. However, the addition of 1.3wt.%Cu slightly refined the secondary dendritic arm spacings (λ₂). It was observed that Cu additions increased the hardness of the Zn-8wt.% Al alloy, due to strengthening mechanisms solution-solid and τ’-Al₄Cu₃Zn intermetallic particles.

BANKING MEMBERS:
Presidente - 2345599 - BISMARCK LUIZ SILVA
Externo ao Programa - 1652765 - MAURÍCIO MHIRDAUI PERES
Externo ao Programa - 1938946 - NICOLAU APOENA CASTRO