Abstract
When maraging steel is austenitized, the reversion from martensite to austenite takes place via diffusionless shear mechanism (martensitic reversion). It is thought that the austenite formed by martensitic reversion (martensitically reversed austenite) contains high-density lattice defect. However, it is impossible to observe martensitically reversed austenite directory, because austenite is unstable at ambient temperature in maraging steel. In this study, we focused on a high austenite stabilization effect of carbon and an austenite stabilizing heat treatment consisting of three-step solid-solution annealing was applied to a 18%Ni-C steel. As a result, martensitically reversed austenite remained fully stable at room temperature through the unique heat treatment. After some microstructural characterizations, the following were mainly found. The martensitically reversed austenite has a fine lath structure with high dislocation density inherited from the lath martensite. While, the crystallographic texture of the austenite was the same as that of the original austenite before martensitic transformation.

Speaker Biography
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Abstract
The early 21st century is experiencing a formidable challenge related to materials extraction and processing. Those core industrial activities will have to ultimately provide more than 9 billion inhabitants with commodities such as steel or fertilizer at an unprecedented rate, while mitigating environmental or societal impacts. In that perspective, higher education institutions have the mission to prepare students to shape the technological paradigms for such challenges, and Allanore argues that it all starts with the fundamentals of materials extraction, metals in particular. Allanore will present his recent endeavor in teaching the fundamentals of chemical metallurgy to undergraduate students at the Massachusetts Institute of Technology, prior to opening a discussion on the possible future of such classes in connection with online education.

Abstract
Wondering how a young person—a freshly graduated high school student—chooses his or her field of study in college, Hosemann always asks new students: "Why did you choose your field of interest? Why material science?" Common answers are that someone in the student’s past mentioned it previously or works in a related field or that the student had a teacher or college advisor who guided them in making the selection of the field of study. But why and how would a student who is not exposed to a good engineering background choose materials science, a field not widely accessible in pre-college education?

While physics and chemistry are often featured on public platforms, such as newspapers or TV, and engineering is in every student’s life through the use of engineered items, such as phones and cars, material science utilizing physics and chemistry to enable engineering solutions is often not on a student’s mind when choosing scientific disciplines or career paths. While this topic is of immediate interest to academics, it bridges further towards a general public perception of what is needed in everyday life to make devices work. In this talk, the question above will be discussed by asking "What do material scientists do?" in a nonprofessional fashion in order to give thought for outreach activities.