Titanium Alloy Composites Research Articles

Effects of interfacial strength on fatigue crack growth in a fiber-reinforced titanium-alloy composite: Chan, K.S. and Davidson, D.L. Metall. Trans. A June 1990 21A, (6), 1603–1612

In recent years, there has been a renewed interest in understanding the mechanical properties and microstructural characteristics of aluminum alloys containing lithium, because of their potential for extensive use in aerospace applications. In the present paper the fatigue crack propagation behavior of aluminum alloy 2020 (AlCuLiMnCd) in the peak strength temper is examined over a wide range of growth rates (from 10−6 to 10−11 m cycle−1). It was found that alloy 2020 shows crack propagation rates that are up to an order of magnitude slower at intermediate ΔK levels and up to two orders of magnitude slower in the near-threshold region, when compared with aluminum alloy 7075 under conditions of similar yield strength, load ratio, frequency and environment. Extensive analyses of the crack path for alloy 2020 reveal that pronounced deflection and branching of the fatigue crack occur at all growth rate levels as a result of a highly crystallographic mode of crack advance. The micromechanisms of fatigue crack growth in alloy 2020 are examined in terms of crack profile, fracture surface features, microstructure and environment.

A study of the reaction zone in an SiC fiber-reinforced titanium alloy composite

Results on several aspects of a SiC fiber-reinforced IMI-829 (α-titanium alloy) metal matrix composite (MMC) are presented. Scanning Auger microscopy (SAM) of SiC fibers reveals a high concentration of oxygen which varies across the diameter of the fibers. It also shows that composition of SiC changes across the diameter and, for the most part, is carbon-rich nonstoichiometric SiC. Transmission electron microscopy (TEM) of thin MMC foils shows the presence of TiC and TiSi2 in the reaction zone. Postfabrication thermal exposures of MMC s at 975 °C lead to void formation in the reaction zone. Concentration profiles of various elements across the reaction zone reveal a buildup of Zr, Nb, and Si and a decrease of Ti, Al, and Sn in the matrix around the reaction zone. Void formation in the reaction zone has been explained by the relatively high flow of Si atoms to the matrix leading to an accumulation of vacancies in the reaction zone which condense to form voids. In addition, an enhancement of hardness in the matrix around the reaction zone has been attributed to a strengthening of the matrix by solid solution and precipitation hardening, together with a contribution from residual stresses.

Interfacial reactions in titanium-matrix composites

A study of the interfacial reaction characteristics of SiC fiber-reinforced titanium aluminide and disordered titanium alloy composites has determined that the matrix alloy compositions affect the microstructure and the distribution of the reaction products, as well as the growth kinetics of the reaction zones. The interfacial reaction products in the ordered titanium aluminide composite are more complicated than those in the disordered titanium-alloy composite. The activation energy of the interfacial reaction in the ordered titanium aluminide composite is also higher than that in the disordered titanium alloy composite. Designing an optimum interface is necessary to enhance the reliability and service life at elevated temperatures.

Effect of the composition of titanium alloys on their corrosion resistance

Effect of the composition of titanium alloys on their corrosion resistance

TiおよびTi合金のイナートガス・アーク溶接に関する研究(第1報)

In this investigation, were studied how the properties were changed when various composition of titanium alloys were heat treated (heating and tempering), in order to study the composition ranges of strong titanium alloys.Consequently, found that rather much alloying element, for example 7-15%Mn, must be added to titanium so as to obtain strong titanium alloys. And to strengthen still more these and other titanium alloys (α+β titanium alloys containing a small amount of β-stabilizer, such as 2%Al-2%Mn-Ti alloy), the alloy have only to be quenched from over (β)/(α+β) transformation temperature according to their composition.The structure in strong titanium alloys obtained with above method are as follows :1) Serrated α(α') in α titanium alloys.2) Acicular α(α')+β in α+β titanium alloys containing a small amount of β-stabilizer.3) β+fine α' or β only in α+β titanium alloys containing a large amount of β-stabilizer.And the hardness in these titanium alloys was Hv. 400 to 550.

TiおよびTi合金のイナートガス・アーク溶接に関する研究(第3報)

Titanium can alloy with almost all elements, but all of these have not good weldability.In this investigation, were studied as to what structure and what composition of titanium alloys had good weldability.Consequently, found that a or α+β titanium alloys containing a small amount of alloying elements, for instance, such as 3% Al-Ti alloy (α) or 2% Al-2% Mn-Ti alloy (α+β) had good weldability. And titanium alloys, seemed to have good weldability, were obtained adding to titanium less than 5% Al or 0.2% C (as α-stabilizer) and less than 4% Mn or 3% Fe (as β-stabilizer). Also, ternary titanium alloys have good weldability, if the total of α-and β-stabilizer is less than 6 % (however, β-stabilizer<α-stabilizer).Then, the structures in weld metal (as welded) of titanium alloys which thought to have good weldability are as follows :1) Coarse serrated α in α titanium alloys.2) Coarse acicular α in α+β titanium alloys.And the hardness in these weld metals was Hv. 200-300.

TiおよびTi合金のイナートガス・アーク溶接に関する研究(第4報)

In this investigation, were studied how the properties were changed when various composition of titanium alloys were heat treated (heating and tempering), in order to study the composition ranges of strong titanium alloys.Consequently, found that rather much alloying element, for example 7-15%Mn, must be added to titanium so as to obtain strong titanium alloys. And to strengthen still more these and other titanium alloys (α+β titanium alloys containing a small amount of β-stabilizer, such as 2%Al-2%Mn-Ti alloy), the alloy have only to be quenched from over (β)/(α+β) transformation temperature according to their composition.The structure in strong titanium alloys obtained with above method are as follows :1) Serrated α(α') in α titanium alloys.2) Acicular α(α')+β in α+β titanium alloys containing a small amount of β-stabilizer.3) β+fine α' or β only in α+β titanium alloys containing a large amount of β-stabilizer.And the hardness in these titanium alloys was Hv. 400 to 550.