Interfacial microstructure design and mechanical properties of the Ti–10Mo double harmonic alloy through powder metallurgy

Heterogeneous metallic materials are expected to realize the strength-toughness synergy. The interface, i.e., diffusion area, is a key factor in determining mechanical properties. In this work, Ti-10Mo chemical and structural double harmonic (CSDH) specimens with different interfacial widths and microstructures were prepared through a powder metallurgy method. All CSDH specimens exhibit similar microstructure features. From the Ti area to Mo, the feature changes in the order of blocky α-Ti grains, long acicular martensite, short acicular martensite, tiny white dot grains, and flat gray β(S) zone surrounding white β-Mo zones. However, the width of diffusion area, i.e., the interfacial width, increases with the diffusion time. The width of α' martensite zone increases gradually to a plateau, but an ever-increase in the width of α" martensite zone. The increased interfacial width ensures high strength, meanwhile the transformation-induced plasticity occurring in the metastable α" martensite zone guarantees favorite elongation. Thus, all CSDH specimens after diffusion from 1 to 8 h display excellent mechanical properties (960 to 1070 MPa for σb and around 10% for εf). The findings can help to develop new heterogeneous metallic materials with strength-toughness synergy and enrich its strengthening-toughening theory.