我们报告了一种新型的双峰共晶（Ti 63.5 Fe 26.5 Co 10）82 Nb 12.2 Al 5.8合金的微观组织演变和相应的力学行为，这些合金是由各种玻璃含量的研磨后合金粉末的半固态烧结（SSS）处理而成的铣削时间。结果表明，随着研磨时间的增加，研磨后的合金粉末具有更均匀的元素分布和更高的玻璃相含量。相应地，尽管SSSed块状合金具有bccβ-Ti，bcc B2 Ti（Fe，Co）和fcc Ti 2相同的组成相（Co，Fe），它们的共晶结构包含bccβ-Ti和bcc B2 Ti（Fe，Co）从不规则共晶转变为部分粗共晶，再到细孔共晶基质，最后演变为典型的纳米和超细层状共晶基质。有趣的是，这是首次报道层状共晶基质具有双峰结构，该结构由纳米和超细晶粒的B2 Ti（Fe，Co）和bccβ-Ti薄片交错而成。与共晶结构的演变相对应，SSSed块状合金的屈服强度和塑性应变逐渐增加。特别是，SSSed双峰共晶合金具有2050 MPa的超高屈服强度和19.7％的大可塑性，优于同类产品。从理论上讲
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Bimodal eutectic titanium alloys: Microstructure evolution, mechanical behavior and strengthening mechanism
We report a novel microstructure evolution and corresponding mechanical behavior of bimodal eutectic (Ti63.5Fe26.5Co10)82Nb12.2Al5.8 alloys processed by semi-solid sintering (SSS) of the as-milled alloy powders with various glass contents resulted from various milling times. Results show that the as-milled alloy powders have more homogeneous element distribution and higher content of glassy phase with increased milling time. Correspondingly, although the SSSed bulk alloys possess the same constituted phases of the bcc β-Ti, bcc B2 Ti(Fe, Co) and fcc Ti2(Co, Fe), their eutectic structures containing bcc β-Ti and bcc B2 Ti(Fe, Co) evolve from irregular eutectic, to partial coarse eutectic, to fine cellular eutectic matrix, and finally to typical nano and ultrafine lamellar eutectic matrix. Interestingly, it is the first time to report that the lamellar eutectic matrix has an bimodal structure consisting of interleaving nano- and ultrafine-grained B2 Ti(Fe, Co) and bcc β-Ti lamellae. Corresponding to the evolution of eutectic structure, the SSSed bulk alloys exhibit a gradual increase in yield strength and plastic strain. Especially, the SSSed bimodal eutectic alloy has ultra-high yield strength of 2050 MPa and large plasticity of 19.7%, superior to those of equivalent counterparts. Theoretically, strengthening mechanism of the SSSed bimodal eutectic alloy can be mainly rationalized as ordering strengthening of B2 superstructured Ti(Fe, Co) and coherency strengthening between bcc β-Ti and bcc B2 Ti(Fe, Co) lamellae inside the lamellar eutectic matrix.