Abstracts Book - IMRC 2018

• SE1-O011 Invited Talk
THE MICROSTRUCTURAL EVOLUTION AND MECHANICAL
BEHAVIOR Fe AND Cr MODIFIED Ti-13Cr(wt.%)
Carl Boehlert 1 , Joann Ballor 1 , Vahid Khademi 1
1 Michigan State University, chemical engineering and materials science, United States.
Titanium (Ti) is a transition metal characterized by its low density, corrosion
resistance, and biocompatibility, among other attractive features. To improve the
mechanical properties, such as strength, other elements are alloyed with Ti. Alloying
elements are classified as α stabilizers, neutral elements, or β stabilizers. Typical Ti
alloys are classified into three categories: α, α+β, or β. β alloys have exhibited very
high strengths after heat treatment, which induces a phase transformation the
body-centered cubic (β) phase to the hexagonal close packed α phase or the
hexagonal ω phase. The ω phase forms in the β matrix through quenching, heat
treatment, or deformation, and microstructures containing the ω phase tend to
exhibit significantly higher hardnesses and strengths than their counterpart α+β
microstructures. Even though the ω phase tends to embrittle the microstructure,
controlling both the β grain size before heat treatment and the volume fraction of
the ω phase after heat treatment can reduce the embrittlement effects. The ω
phase can also improve fatigue properties by inhibiting fatigue crack propagation
(FCP). Microstructures exhibiting slower FCP, adequate elongation-to-failure, high
strength, corrosion resistance, and low density are highly sought after for structural
applications. Based on the literature, one means to obtain such microstructures in
β-Ti alloys could be through low-temperature aging to induce the ω phase
transformation. However, there is not a clear understanding of the optimal amount,
distribution, and morphology of the ω phase needed to achieve microstructures
with a desirable balance of properties. One goal of the research to be presented
was to better understand processing-microstructure-property relationships of iron
(Fe) and aluminum (Al) modified Ti-13wt.%chromium alloys, containing the b, a, and
ω phases, to be able to design microstructures that achieve a desirable combination
of tensile, creep, and fatigue properties.
Acknowledgment:
This work was supported by the Department of Energy Basic Energy Science
Program.
Keywords: titanium, microstructure, mechanical behavior
Presenting authors email: boehlert@egr.msu.edu