Pre melting in iron and iron alloys: ab initio calculations and high P-T experiments on iron, iron alloys and other materials

Lead Research Organisation: University College London
Department Name: Earth Sciences

Abstract

The questions this proposal seeks to address are these: are the pre-melting effects suggested to occur in iron at the conditions of the Earth's inner core really there, are they seen across PT space in both iron and iron alloys, and are they seen in other materials? If the answer turns out to be "yes", all models for the dynamics and evolution of the Earth's core will have to be re-evaluated.

For over 80 years, the Earth's core has been considered to consist of an iron-nickel alloy, with a few percent of light alloying elements. The pressure range in the core is ~135

Planned Impact

1. Who will benefit:
The knowledge arising from this research will lead to a better understanding of the composition, structure and evolution of the Earth's inner core. This fundamental knowledge will primarily interest academics concerned with the evolution of the Earth and other terrestrial planets - geochemists, geophysicists and planetologists. The applied knowledge resulting from this project will benefit metallurgists and material scientists. The general public have an enduring interest in the evolution of the Earth and the planets in our solar system. The media are also keen to report results which have broad public appeal.

2. How will they benefit:
Geochemists, geophysicists and planetologists will gain deeper insight into the physical and chemical properties of planetary cores, which, in turn, may well have implications for our understanding of processes occurring in the mantle. This research will lead to constraints on the material properties of the deep Earth allowing seismologists to better interpret their data. Metallurgists and material scientists will benefit from the new data on pre-melting phenomena and the physical properties of the iron alloys at very high pressures and temperatures. Also, these data are essential in modeling high energy impacts using hydrodynamic codes, where fundamental material properties are used to determine the response of targets to impactors. Even though the end users of this type of knowledge are dominantly academics, the results have great media appeal because of human curiosity concerning the Earth on which we live.

3. What will be done:
Academic beneficiaries: We shall integrate our work into the recently established Paris-UCL Research Exchange programme which aims to foster collaboration between scientists working on the deep Earth at UCL and at the Institut de Physique du Globe de Paris. Broader engagement with material scientists will be made through the UCL Centre for Materials Research, and that with hydrodynamic modellers will be made through the UCL Centre for Planetary Sciences.

Training: One PDRA will be trained in high-pressure/high-temperature experimental techniques, measurement of physical properties and diffraction studies, and will also gain experience working at international large-scale facilities (e.g., APS, ISIS). The other PDRA will gain expertise in simulation methods; this is an area which has been identified as having a national shortfall of trained researchers.

General public: We will set up a Facebook page called "The Earth's Core @UCL" which will give up-to-date background information about the Earth's core together with highlights from our research here at UCL and links, with easy, accessible, explanation, to high quality research elsewhere.

4. Milestones/measures of success
Key outputs will be publications in scientific journals and presentation of the work at international and national conferences. Possible exit-jobs of the PDRAs include work in academia, industrial materials research, computing and mathematical modeling (including the business and financial sectors) as well as scientific administration and journalism.

Publications

10 25 50
 
Description We have ruled OUT Fe7C3 as a major component of the Earth's inner core. We have now found a number of Fe-C-Si alloys that do fit the observed elastic data. This is the first time that a match has been made.
Exploitation Route We need to look at thermodynamics stability of the candidate alloys, together with the partitioning behaviour of the light elements.
Sectors Education,Other

 
Description Box Office Blunders 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact A UCL Earth Sciences workshop which seeks out the scientific blunders in the blockbuster film, "The Core". This highly interactive workshop introduces secondary school students to the physics of the interior of the Earth, as well as giving a brief insight into the techniques used by scientists to probe the deep depths of the planet beneath our feet.

The perception of what actually goes on inside the Earth was significantly altered as a result of this activity
Year(s) Of Engagement Activity 2012,2013,2014,2015,2016
URL http://www.ucl.ac.uk/EarthSci/impact/bob/index.html
 
Description Facebook page for activities relating to the Earth's Core 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact A facebook page to promote research activity both within and without UCL about the Earth's core
Year(s) Of Engagement Activity 2015,2016
URL http://www.facebook.com/UCLEarthsCore
 
Description Rocks and Minerals 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Rocks and Minerals: learn about the different types of rocks and minerals that make up our planet and those in our solar system. KS2
We run a series of Rocks and Minerals workshops for children in Key Stage 2, Years 3 and 4 (ages 7-9) to meet their curriculum needs via the statutory requirement: compare and group together different kinds of rocks on the basis of their appearance and simple physical properties. The children have a guided hands-on experience, learning also about the Earth as a whole through discussion and questions at the end of each session. We have three stations with sedimentary rocks, igneous and metamorphic rocks, and minerals. We find that the children are fascinated by, for example, the beauty yet poisonous nature of bismuth, the remarkable intergrowth of pyrite (which they always think is gold) and the age of a meteorite.
Year(s) Of Engagement Activity 2015,2016,2017,2018,2019
URL https://www.ucl.ac.uk/earth-sciences/impact/for-public/public-list/school-visits
 
Description Schools visits 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact 90 pupils attended our Department for workshop activities on Rocks&Minerals, Earthquakes and Volcanoes
Year(s) Of Engagement Activity 2019
 
Description The Earth's Core - public talk Festival of Geology, Brandeston Village, Sussex Geological Society, UCL Open Days 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact A talk about the deep interior of the Earth for a general audience
Year(s) Of Engagement Activity 2017,2018,2019
 
Description Volcanoes and Earthquakes 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact We run a series of Volcanoes and Earthquakes workshops for children in Key Stage 3 and 4. This meets their curriculum needs via the statutory requirement: volcanoes and earthquakes. In this activity the children are taught about the origin and global impact of volcanoes; they then build a volcano themselves, analysing its formation and structure. Earthquakes are taught by demonstration in conjunction with the use of an IPhone and the iSeismometer app.
Year(s) Of Engagement Activity 2015,2016