Abstract

In this paper, the Widmanstätten microstructure in an extruded near-α titanium alloy (Ti-5.5Al-2Zr-1Mo-2.5V) pipe was changed effectively by solid solution treatment at 920 °C for 2 h. The treatment produced intermittent lamellar α and discontinuous α grain boundaries (α_GB), and aging at 450 °C for 2 h introduced a high density of nanosized secondary α (α_s). The microstructure consisted of the lamellar α, α_GB and transformed β demonstrated a good combination of yield strength 1064 MPa and elongation 10.5%. Severe plastic deformation occurred inside the lamellar α during the tensile process, resulting in high-density dislocation tangles and dislocation cells. Furthermore, the stretching imposed on the tensile sample before aging generated dislocations, which piled up near the α/β interface. Thus, a coordinated deformation between lamellar α and transformed β, and the resultant strain partition contributed to an improvement in the ductility. Moreover, dislocation motion was effectively obstructed near the α/β interfaces, which dramatically strengthened the alloy. A solid solution at a middle temperature in the α + β region and aging at a low temperature provided an effective way to improve the strength and ductility simultaneously in titanium alloys with Widmanstätten microstructure.

中文翻译：

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具有Widmanstätten微结构的Ti-5.5Al-2Zr-1Mo-2.5V合金管中的精细二次α相诱导强化

摘要

本文通过在920°C下固溶处理2 h有效地改变了挤压的近α钛合金（Ti-5.5Al-2Zr-1Mo-2.5V）管中的Widmanstätten组织。该处理产生间歇层状α和不连续的α晶界（α _GB），并在450老化℃下2小时引入纳米尺寸的二次高密度的α（α_小号）。微结构包括层状的α，α _GB并转化β表明的屈服强度1064兆帕，伸长率10.5％的良好结合。板层内部发生严重的塑性变形α在拉伸过程中，导致高密度的位错缠结和位错单元。此外，在老化之前施加在拉伸样品上的拉伸产生位错，其在α / β界面附近堆积。因此，层状α与相变β之间的协调变形以及所产生的应变分配有助于延展性的提高。而且，在α / β界面附近有效地阻止了位错运动，从而显着增强了合金。α  +  β中温的固溶体 区域和低温时效提供了一种有效的方法，可同时提高具有Widmanstätten显微组织的钛合金的强度和延展性。