Alloy Design of Ti Alloys Using Ubiquitous Alloying Elements and Characteristics of Their Levitation-Melted Alloys

Abstract

The + type Ti-5.5Al-2Fe and type Ti-2.5Fe-2Mn-2Zr alloys have been theoretically designed, for the modification of Ti-6Al-4V and the achievement of the high tensile strength more than 1000 MPa at the solution treatment state, respectively, using ubiquitous alloying elements in order to establish the strategic method for suppressing utilization of rare metals. The utilization of the cold crucible levitation melting (CCLM) is very useful for the production of ingots, because titanium is very chemically reactive at high temperature. The experimental alloys with high purity and without contaminations from a crucible were prepared, and the homogeneous melt was also achieved by the diffusion mixing effect of CCLM. The microstructure, phase stability, strength, corrosion-resistance and workable properties of the design Ti-5.5Al-2Fe alloy, were comparable to those of Ti-6Al-4V. In contrast, the solution heat treated Ti-2.5Fe-2Mn-2Zr alloy showed the tensile strength of 1200 MPa, and the 1.3 times increase in the specific strength compared with Ti-15Mo-5Zr-3Al. The alloy design can be successfully carried out even using ubiquitous alloying elements by the d-electrons concept, which leads to the establishment of one method for the strategic utilization of rare metals.

Property-Control of TiNi System Intermetallics and Their Characteristics

“…12 indicates that an increase in the bond strength between atoms leads to high oxidation resistance. This agrees with the results obtained from the active corrosion rate in 10%H 2 SO 4 at 343 K 44) and the weight loss in Na 2 SO 4 -45 mol%NaCl molten salt at 923 K 19) for of various Ti alloys.…”

“…7,18,19) In the beginning of this alloy design, both values in the tensile strength and the temperature in start for martensite transformation (Ms-temperature) of previously reported TiNi compounds, [20][21][22][23][24][25][26][27][28][29][30] were represented in the Md and Bo diagram, in order to predict their values of designed intermetallics, as described in the following section 2.2 and 2.3. In addition to binary compounds, ternary (or more multi-components) compounds, for example, (M 1Àx Y x )Ti are also located on the Md and Bo map, simply taking the compositional average of the Bo and Md parameters.…”

Compositional Optimization of Al-Mn-X Alloys and, Their Tensile and Corrosion Properties

“…In this study, the evaluation of mechanical properties by ¦Mk is tried in order to establish simplified alloy design for practical application. 7,16) Al-1.5 mass% Mn was chosen as the binary basic alloy system showing aluminum solid solution, and Ca, Mg, Ti and Zn were chosen as ternary alloying elements. ¦Mk of Al-1.5Mn-X alloys was decided to be less than 0.017, adjusting by amount of ternary alloying elements.…”

“…A target region showing high level in the ultimate tensile strength for ¢ Ti alloy design can be specified concretely adjusting the Bo and Md values on the Bo-Md diagram. 2,7) Therefore, the d-electrons concept has been applied to design of the high performance metallic materials such as Ni, Ti, Mg and Fe-based alloys, etc. 510) For alloys the average values of Bo and Md are defined by taking the compositional average as mentioned in detail in section 3, which is easy to use in practical application, compared with other alloy design methods 1113) .…”

Optimization of Strength, Ductility and Corrosion Resistance in Ti-Mo Base Alloys by Controlling Mo Equivalency and Bond Order

“…Note that the Bo is a measure of the covalent bond strength between the titanium and the alloying element. 24,25) Matsugi et al 26) reported that a ratio of weight loss to initial weight obtained from the Ti-10Mo-2Fe deformation mode Slip Twinning Fig. 1 Changes in the yield strength (YS) and the uniform elongation (uEL) against the Mo equivalency in Ti-Mo base alloys, 16) showing that a combination of high strength and significant elongation can be achieved at the Mo equivalency between 15.3 and 18.7 mass% (solid marks).…”