TY - JOUR

T1 - Restoration mechanisms at moderate temperatures for As-Cast ZK40 magnesium alloys modified with individual Ca and Gd additions

AU - Buzolin, Ricardo Henrique

AU - Guimaraes, Leandro Henrique Moreno

AU - Díaz, Julián Arnaldo Ávila

AU - Silva, Erenilton Pereira da

AU - Tolnai, Domonkos

AU - Mendis, Chamini L.

AU - Hort, Norbert

AU - Pinto, Haroldo Cavalcanti

N1 - The authors would like to thank the Brazilian Synchrotron Light Laboratory (LNLS) CNPEM/MCTIC for the use of the XTMS beamline. RHB acknowledges the CD-Laboratory for Design of High-Performance Alloys by Thermomechanical Processing with the support of the Christian Doppler Forschungsgesellschaft. L.H.M.G. acknowledges the financial Support of Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES) (Process No. 88882.180165/2018-01). J.A.Á.D. acknowledges CNPq for a postdoc scholarship (Grant No. 150215/2016-9). The authors sincerely acknowledge Maria Cecilia Poletti for fruitful and meaningful discussions. Open Access Funding by the Graz University of Technology.

PY - 2020/12/16

Y1 - 2020/12/16

N2 - The deformation behaviour of as-cast ZK40 alloys modified with individual additions of Ca and Gd is investigated at 250◦C and 300◦C. Compression tests were carried out at 0.0001 s−1 and 0.001 s−1 using a modified Gleeble system during in-situ synchrotron radiation diffraction experiments. The deformation mechanisms are corroborated by post-mortem investigations using scanning electron microscopy combined with electron backscattered diffraction measurements. The restoration mechanisms in α-Mg are listed as follows: the formation of misorientation spread within α-Mg, the formation of low angle grain boundaries via dynamic recovery, twinning, as well as dynamic recrystallisation. The Gd and Ca additions increase the flow stress of the ZK40, which is more evident at 0.001 s−1 and 300◦C. Dynamic recovery is the predominant restoration mechanism in all alloys. Continuous dynamic recrystallisation only occurs in the ZK40 at 250◦C, competing with discontinuous dynamic recrystallisation. Discontinuous dynamic recrystallisation occurs for the ZK40 and ZK40-Gd. The Ca addition hinders discontinuous dynamic recrystallisation for the investigated temperatures and up to the local achieved strain. Gd addition forms a semi-continuous network of intermetallic compounds along the grain boundaries that withstand the load until their fragmentation, retarding discontinuous dynamic recrystallisation.

AB - The deformation behaviour of as-cast ZK40 alloys modified with individual additions of Ca and Gd is investigated at 250◦C and 300◦C. Compression tests were carried out at 0.0001 s−1 and 0.001 s−1 using a modified Gleeble system during in-situ synchrotron radiation diffraction experiments. The deformation mechanisms are corroborated by post-mortem investigations using scanning electron microscopy combined with electron backscattered diffraction measurements. The restoration mechanisms in α-Mg are listed as follows: the formation of misorientation spread within α-Mg, the formation of low angle grain boundaries via dynamic recovery, twinning, as well as dynamic recrystallisation. The Gd and Ca additions increase the flow stress of the ZK40, which is more evident at 0.001 s−1 and 300◦C. Dynamic recovery is the predominant restoration mechanism in all alloys. Continuous dynamic recrystallisation only occurs in the ZK40 at 250◦C, competing with discontinuous dynamic recrystallisation. Discontinuous dynamic recrystallisation occurs for the ZK40 and ZK40-Gd. The Ca addition hinders discontinuous dynamic recrystallisation for the investigated temperatures and up to the local achieved strain. Gd addition forms a semi-continuous network of intermetallic compounds along the grain boundaries that withstand the load until their fragmentation, retarding discontinuous dynamic recrystallisation.

KW - Characterisation

KW - Deformation behaviour

KW - Electron microscopy

KW - In-situ diffraction

KW - Magnesium alloys

KW - Restoration mechanisms

KW - Engineering

UR - http://www.scopus.com/inward/record.url?scp=85098983382&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/fd83b17f-93a5-3f0c-9061-3a6a3ddcd86e/

U2 - 10.3390/cryst10121140

DO - 10.3390/cryst10121140

M3 - Journal articles

AN - SCOPUS:85098983382

VL - 10

SP - 1

EP - 22

JO - Crystals

JF - Crystals

SN - 2073-4352

IS - 12

M1 - 1140

ER -