Body-centered cubic (BCC) medium-entropy alloys (MEAs) are characterized by high strength, low ductility and often high density due to containing much refractory elements. In this paper, a series of BCC Ti-Al-Nb-Zr medium-entropy alloys were constructed by adding different contents of Al to Ti₆₇Nb₁₆Zr₁₇ base alloy composed of α and β phases. It is shown that an enough addition of Al can depress the formation of α phase, resulting in single BCC structure. (Ti₆₇Nb₁₆Zr₁₇)₈₇Al₁₃ alloy has the best comprehensive mechanical property as the strength-ductility trade-off is well overcome. Its specific strength is up to 230 MPa g⁻¹ cm³ and its elongation is also as high as 18.5% in the as-cast state, better than most existing medium- and high-entropy alloy. It is revealed that abundant nanoscale chemical short-range order (CSRO) in the matrix phase plays an important role in the mechanical response of this alloy.

体心立方 (BCC) 中熵合金 (MEA) 具有高强度、低延展性和由于含有大量难熔元素而通常具有高密度的特点。本文通过在由α相和β相组成的Ti ₆₇ Nb ₁₆ Zr ₁₇基合金中添加不同含量的Al，构建了一系列BCC Ti-Al-Nb-Zr中熵合金。结果表明，添加足够的 Al 可以抑制 α 相的形成，从而导致单一的 BCC 结构。(Ti ₆₇ Nb ₁₆ Zr ₁₇ ) ₈₇ Al ₁₃合金由于很好地克服了强度-延展性的折衷，综合力学性能最好。比强度高达230 MPa·g⁻¹ cm ³，铸态伸长率也高达18.5%，优于现有的大多数中、高熵合金。结果表明，基体相中丰富的纳米级化学短程有序 (CSRO) 在该合金的机械响应中起着重要作用。