Microstructure engineering of titanium alloys via small boron additions
Microstructure engineering of titanium alloys via small boron additions
复制标题
DOI：
10.1007/s12572-011-0033-z
复制
发表时间：
2010-12-01
影响因子：
0.9
通讯作者：
Miracle, D. B.
中科院分区：
文献类型：
--
作者：
Tamirisakandala, S.;Miracle, D. B.
早在20世纪50年代，人们就对钛合金中加入硼进行了一些研究，目的是提高其硬度和强度。由于缺乏机械性能组合以及对添加硼对加工-显微组织-性能关系的影响的了解不足，这些努力中的大多数都没有导致成功的转变。最近，一组研究人员对硼改性钛合金进行了严格评估，以评估其在航空航天应用中的适用性。在这些评估过程中，发现了硼改性钛合金提供的几个独特的机会。硼基本上不溶于钛，以细小的TiB晶须的形式析出。在钛合金中添加少量的硼（约0.1 wt%），在铸态条件下，晶粒尺寸显著变细。TiB析出相的存在限制了晶粒在高温下的生长，甚至在β横截面以上。总之，这些特性为开发经济实惠的钛合金热机械加工路径提供了潜力。最近的研究还表明，通过添加少量硼，传统钛合金的强度和刚度可以提高20%，同时保持可接受的断裂和疲劳性能。在本文中，我们回顾了这类新型钛合金，并描述了作者及其合作者在最近的几项研究中发现的通过微观结构工程获得的独特优势。
Several studies, dating back to 1950s, were conducted on the addition of boron to titanium alloys, with an aim to improve the stiffness and strength. The majority of these efforts did not lead to successful transition due to shortfalls in mechanical property combinations and insufficient understanding of the effect of boron addition on processing-microstructure-property relationships. Recently, a team of researchers critically evaluated boron-modified titanium alloys to assess their applicability for aerospace applications. Several unique opportunities offered by boron-modified Ti alloys were discovered during these evaluations. Boron is essentially insoluble in titanium and precipitates as fine TiB whiskers. Small additions (similar to 0.1 wt%) of boron to titanium alloys were found to result in dramatically finer grain sizes in the as-cast condition. The presence of TiB precipitates restricts the grain growth at elevated-temperatures, even above the beta transus. Together, these features offer the potential to develop affordable thermo-mechanical processing paths for titanium alloys. This recent work also demonstrated that, via small boron additions, the strength and stiffness of conventional titanium alloys could be increased up to 20% while retaining acceptable fracture and fatigue properties. In this paper, we review this new class of titanium alloys and describe unique benefits obtained via microstructure engineering that were discovered in several recent studies by the authors and their collaborators.