Grand alloys-A new strategy for alloy design by combination of complementary alloys of a single fami
Abstract
The global demand for stronger and lighter alloys for engineering applications has brought interest in the design of new titanium al,loys. However, the potential for property enhancement to push the strength-ductility envelope of titanium alloys is rather limited a,nd has been exhausted. To overcome this challenge, we propose a new strategy for alloy design where we make alloys of alloys or wh,at we call grand alloys. In this new paradigm of alloy design, the ingredients are alloys as opposed to pure elements. Our approac,h exploits the diversity of properties that has already been attained in conventional alloys and seeks to achieve synergistic effect,s by combining them.Additive manufacturing (AM) is a critical enabler to synthesis grand alloys. Fast cooling rates in beam-based AM, limit the diffusion between constituent alloys and preserve their composition and properties. Of particular interest for this propo,sal is the use of powder-fed direct energy deposition (DED). The multi-material deposition capability of the DED process offers unpr,ecedented possibilities to spatially distribute the ingredient alloys. What is more, using AM allows us to make near-net shape compo,nents that could result in significant cost savings as machining titanium alloys is challenging.In this three-year proposal, we plan, to establish the AM process-microstructure-properties relationships for the legacy alloy Ti-6Al-4V, a metastable beta titanium allo,y (which we identify through a high-throughput combinatorial study), and for a Ti grand alloy made of Ti-6Al-4V and metastable beta,titanium. The ingredient alloys are selected to achieve the co-existence of phases (alpha prime and beta) that is otherwise impossib,le to realize through conventional processing routes. In addition, the ingredients are chosen to offer complementary properties. The, martensitic phase has high strength while the metastable beta phase offers high ductility enabled by multiple deformation mechanism,s. We will use in-operando X-ray diffraction studies to establish a fundamental understanding of the process-microstructure relation,ships in individual alloys as well as those of their co-deposition under AM processing conditions. In addition, we will correlate re,constructed 3D electron backscatter diffraction (3D-EBSD) maps with both in-operando X-ray diffraction and in-situ tensile tests. Th,e former unravels solidification pathways and its effect on microstructure while the latter elucidates key microstructural features,governing the deformation of these alloys.The novel paradigm of grand alloys by the combination of different classes of titanium a,lloys opens new opportunities for alloy design. With appropriate design, the heterogeneity between ingredient alloys with elastic co,mpatibility and efficient load transfer could lead to an excellent combination of properties. While the concept is being explored fo,r titanium alloys in this proposal, it can be expanded to other material systems such as steelsand aluminum alloys.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 08, 2022
- Source ID
- N000142212420
Entities
People
- Atieh Moridi
Organizations
- Cornell University
- Office of Naval Research
- United States Navy