Grain Refinement and Improvement
in Microhardness of AZ91 Mg Alloy Via
Friction Stir Processing
Minal S. Dani and I. B. Dave
Abstract On commercially available die-cast AZ91 magnesium (Mg) alloy, friction
stir processing (FSP) was successfully done with and without pure aluminum powder
in the solid state. In this article, FSP with different process parameters on die-cast
AZ91 Mg alloy was investigated for microstructure, grain size and microhardness
and compared with untreated die-cast AZ91 magnesium alloy. Untreated die-cast
AZ91 Mg alloy showed a dendritic structure having primary α-phase and irregularly
distributed eutectic β-phase (Mg 17 Al 12 ) at the grain boundaries. Due to FSP, breakup
and dissolution of the course network of eutectic β-phase (Mg 17 Al 12 ) with noticeable grain refinement were achieved. Microstructural characterization by optical
and scanning electron microscopy (SEM) of all FSP-treated specimens revealed the
grain refinement and reasonably uniform distribution of aluminum powder observed
in FSPed double pass with aluminum powder specimens. Microhardness studies
confirmed that double-pass friction stir-processed specimens with aluminum powder
in the Mg matrix leads to improvement in hardness.
Keywords Friction stir processing · β-phase (Mg 17 Al 12 ) · Microstructure ·
Microhardness · Magnesium alloy
1 Introduction
Magnesium (Mg) alloys exhibit high mechanical properties and lighter weight which
has fueled considerably analysis activities in recent times targeted primarily for his
or her any development [1]. Aluminum and steel and organic materials are replaced
with Mg alloys for automobile, aerospace, electronics and computer industries due
to lightest structural materials [1–4]. AZ91-grade Mg alloy is widely used for manufacturing die-cast components because, in all verities of Mg alloys, AZ91 is simple
to process into high strength components at a low price that leads to more industrial
applications and more utilization in research and development [5, 6].
M. S. Dani (B) · I. B. Dave
Metallurgy Engineering, GTU, Ahmedabad, Gujarat, India
e-mail: minal@gecg28.ac.in
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
A. K. Parwani et al. (eds.), Recent Advances in Mechanical Infrastructure,
Lecture Notes in Intelligent Transportation and Infrastructure,
https://doi.org/10.1007/978-981-33-4176-0_16
197
in Microhardness of AZ91 Mg Alloy Via
Friction Stir Processing
Minal S. Dani and I. B. Dave
Abstract On commercially available die-cast AZ91 magnesium (Mg) alloy, friction
stir processing (FSP) was successfully done with and without pure aluminum powder
in the solid state. In this article, FSP with different process parameters on die-cast
AZ91 Mg alloy was investigated for microstructure, grain size and microhardness
and compared with untreated die-cast AZ91 magnesium alloy. Untreated die-cast
AZ91 Mg alloy showed a dendritic structure having primary α-phase and irregularly
distributed eutectic β-phase (Mg 17 Al 12 ) at the grain boundaries. Due to FSP, breakup
and dissolution of the course network of eutectic β-phase (Mg 17 Al 12 ) with noticeable grain refinement were achieved. Microstructural characterization by optical
and scanning electron microscopy (SEM) of all FSP-treated specimens revealed the
grain refinement and reasonably uniform distribution of aluminum powder observed
in FSPed double pass with aluminum powder specimens. Microhardness studies
confirmed that double-pass friction stir-processed specimens with aluminum powder
in the Mg matrix leads to improvement in hardness.
Keywords Friction stir processing · β-phase (Mg 17 Al 12 ) · Microstructure ·
Microhardness · Magnesium alloy
1 Introduction
Magnesium (Mg) alloys exhibit high mechanical properties and lighter weight which
has fueled considerably analysis activities in recent times targeted primarily for his
or her any development [1]. Aluminum and steel and organic materials are replaced
with Mg alloys for automobile, aerospace, electronics and computer industries due
to lightest structural materials [1–4]. AZ91-grade Mg alloy is widely used for manufacturing die-cast components because, in all verities of Mg alloys, AZ91 is simple
to process into high strength components at a low price that leads to more industrial
applications and more utilization in research and development [5, 6].
M. S. Dani (B) · I. B. Dave
Metallurgy Engineering, GTU, Ahmedabad, Gujarat, India
e-mail: minal@gecg28.ac.in
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
A. K. Parwani et al. (eds.), Recent Advances in Mechanical Infrastructure,
Lecture Notes in Intelligent Transportation and Infrastructure,
https://doi.org/10.1007/978-981-33-4176-0_16
197