PMID- 36614482
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20230111
IS  - 1996-1944 (Print)
IS  - 1996-1944 (Electronic)
IS  - 1996-1944 (Linking)
VI  - 16
IP  - 1
DP  - 2022 Dec 23
TI  - The Activation Energy of Strain Bursts during Nanoindentation Creep on 
      Polyethylene.
LID - 10.3390/ma16010143 [doi]
LID - 143
AB  - In the present investigation, statistical characterization of strain bursts 
      observed during the load-controlled deformation of high-density polyethylene 
      (HDPE), which arise within the crystalline phase during plastic deformation, was 
      carried out via high-resolution nanoindentation creep experiments. Discrete 
      deformation processes occurred during the nanoindentation creep tests, which 
      indicated that they arose from the break-off of dislocation avalanches, i.e., 
      dislocation climb is a possible mechanism for indentation creep deformation. 
      Characterization of the strain bursts, in terms of the associated height and 
      number, demonstrated that these quantities followed a Gaussian distribution 
      depending on the load and loading rate. This analysis enabled the accurate 
      measurement of creep activation energy. Our method used nanoindentation tests to 
      measure the creep activation energy of HDPE within both the crystalline and 
      amorphous phases. The activation energy of the creep process within the 
      crystalline phase was evaluated using two methods. The frequency of jumps within 
      the crystalline phase, as a function of the strain rate, showed two peaks related 
      to the 5 nm and 10 nm jump sizes that corresponded to the block size within the 
      crystalline lamellae. The results indicated that the intervals coincided with the 
      mean free path of dislocations and the block grain boundaries acted as 
      dislocation barriers. From the dependence of burst frequency on the strain rate 
      and temperature, the activation energy and thermally activated length of the 
      dislocation segment for the plastic slip activation were determined to be 0.66 eV 
      and 20 nm, respectively. Both numbers fit well to the Peterson's model for the 
      nucleation and motion of thermally activated dislocation segments. A similar 
      activation energy resulted from the differential mechanical analysis of the 
      literature for the alpha(I)-transition, which occurred near room temperature in 
      polyethylene. The transition was described as the generation of screw dislocation 
      and its motion along a block grain boundary; therefore, this process is suggested 
      to be the basic mechanism underlying the strain bursts observed in this study.
FAU - Ghomsheh, Mohammad Zare
AU  - Ghomsheh MZ
AUID- ORCID: 0000-0002-2862-4486
AD  - Christian Doppler Laboratory for Lifetime and Reliability of Interfaces in 
      Complex Multi-Material Electronics, CTA, TU Wien, Getreidemarkt 9/164, 1060 
      Vienna, Austria.
FAU - Khatibi, Golta
AU  - Khatibi G
AD  - Christian Doppler Laboratory for Lifetime and Reliability of Interfaces in 
      Complex Multi-Material Electronics, CTA, TU Wien, Getreidemarkt 9/164, 1060 
      Vienna, Austria.
LA  - eng
PT  - Journal Article
DEP - 20221223
PL  - Switzerland
TA  - Materials (Basel)
JT  - Materials (Basel, Switzerland)
JID - 101555929
PMC - PMC9821546
OTO - NOTNLM
OT  - activation energy
OT  - activation volume
OT  - creep
OT  - nanoindentation
OT  - polyethylene
OT  - strain burst
COIS- The authors declare that they have no known competing financial interest or 
      personal relationship that could have appeared to influence the work reported in 
      this paper.
EDAT- 2023/01/09 06:00
MHDA- 2023/01/09 06:01
PMCR- 2022/12/23
CRDT- 2023/01/08 01:28
PHST- 2022/10/21 00:00 [received]
PHST- 2022/12/11 00:00 [revised]
PHST- 2022/12/16 00:00 [accepted]
PHST- 2023/01/08 01:28 [entrez]
PHST- 2023/01/09 06:00 [pubmed]
PHST- 2023/01/09 06:01 [medline]
PHST- 2022/12/23 00:00 [pmc-release]
AID - ma16010143 [pii]
AID - materials-16-00143 [pii]
AID - 10.3390/ma16010143 [doi]
PST - epublish
SO  - Materials (Basel). 2022 Dec 23;16(1):143. doi: 10.3390/ma16010143.