基于Ti-6Al-4V团簇式设计的超高强Ti-Al-V-Mo-Nb-Zr合金

An Ultra-high-strength Ti-Al-V-Mo-Nb-Zr Alloy Designed from Ti-6Al-4V Cluster Formula

设计并用真空铜模吸铸制备了近α型双相Ti-Al-V-Mo-Nb-Zr合金系列,其成分框架满足Ti-6Al-4V的α+β双相团簇式,即α和β相团簇式的比例为12:5。同时,通过多元合金化尤其是改变Zr含量,可将后者改造成具有更高β稳定性的形式[Al-Ti_(14-x)Zr_(x)](Mo_(0.6)Nb_(0.2)V_(1.2)Al),x=0.6~3。这些合金的铸态组织其特征为网篮状,并含有大量针状α'马氏体。随着Zr含量的提高这些合金的晶粒细化,其强度和硬度也随之提高,Zr含量最高的Ti-6.7Al-2.2V-2.1Mo-0.7Nb-10.0Zr合金达到超高强水平,其铸态的拉伸强度为1404 MPa,维氏硬度为451HV,与热处理后的典型超高强钛合金β-21S的性能接近,与在相同条件下制备的Ti-6Al-4V相比其强度和硬度分别提高52%和39%,比强度和比硬度分别提高45%和33%。

The near-αdual-phase Ti-Al-V-Mo-Nb-Zr alloy series were designed and prepared by copper-mold suction casting in this paper.Their compositions fall within the composition framework previously determined for Ti-6Al-4V:theαandβformulas satisfy the ratio of 12:5,but theβpart can be further stabilized,by using multi-element alloying and especially by varying the addition amount of Zr,into the form of[Al-Ti_(14-x)Zr_(x)](Mo_(0.6)Nb_(0.2)V_(1.2)Al),x=0.6~3.The as-cast alloys are all characterized by a basket-weave microstructure containing a large number ofα'martensite needles.With increasing Zr content theα'needles are gradually refined,and the strength and hardness increase accordingly.Among them a Ti-6.7Al-2.2V-2.1Mo-0.7Nb-10.0Zr alloy achieves the ultra-high strength level,with the ultimate tensile strength of 1404 MPa and Vickers-hardness of 451HV,close to the typical ultra-high-strengthβ-21s after heat-treatment.In comparison with Ti-6Al-4V prepared in the identical conditions,the strength and hardness of this alloy exceeds those of Ti-6Al-4V by 52%and 39%,and the specific strength and hardness are increased by 45%and 33%respectively.