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The mechanical properties -tensile strength, yield strength, elongation after fracture, and Vickers hardness- and alloy phases of the dental cast alloys Ti-6%Nb-4%Cu, Ti-18%Nb-2%Cu, and Ti-24%Nb-1%Cu were investigated. Ti-6%Nb-4%Cu consisted of a single α-phase, while Ti-18%Nb-2%Cu and Ti-24%Nb-1%Cu consisted of α- and β-phases. The tensile strengths, yield strengths, and hardnesses of these alloys were higher than those of Ti-5%Cu and Ti-30%Nb; however, their breaking elongations were smaller. These differences in the mechanical properties are attributable to solid-solution strengthening or to precipitation strengthening by the dual-phase (α+β) structure. Thus, Ti-Nb-Cu alloys are suitable for use in high-strength dental prostheses, such as implantretained superstructures and narrow-diameter implants.

Titanium is difficult to machine because of its intrinsic properties. In a previous study, the machinability of titanium was improved by alloying with silver. This study aimed to evaluate the durability of tungsten carbide burs after the fabrication of frameworks using a Ti-20%Ag alloy and titanium with a computer-aided design and computer-aided manufacturing system. There was a significant difference in attrition area ratio between the two metals. Compared with titanium, the ratio of the area of attrition of machining burs was significantly lower for the experimental Ti-20%Ag alloy. The difference in the area of attrition for titanium and Ti-20%Ag became remarkable with increasing number of machining operations. The results show that the same burs can be used for a longer time with Ti-20%Ag than with pure titanium. Therefore, in terms of tool life, the machinability of the Ti-20%Ag alloy is superior to that of titanium.

The mechanical properties -tensile strength, yield strength, elongation after fracture, Vickers hardness, and Young's modulus-and the phases of Ti-Ag alloys were investigated, as prepared with 22.5, 25, 27.5, and 30 mass% Ag. The tensile strength, yield strength, hardness, and Young's modulus of the alloys increase with their Ag content up to 25 mass%, but their breaking elongation decreases. These changes in the mechanical properties are attributed to solid-solution strengthening of the α-titanium phase, to Ti2Ag precipitation, and to the formation of eutectic structures composed of α+Ti2Ag. The addition of Ag, at 25 mass% in particular, improves the mechanical properties of these alloys, making them suitable for high strength dental prostheses, such as implantretained superstructures and narrow-diameter implants.

The purpose of this study was to evaluate the corrosion resistance of experimental Ti-Ag alloys used as dental materials. An elution test and a rest-potential measurement of alloys with 5–30 mass.% Ag were performed in a 1 % lactic acid solution. The amount of Ti ions released from the α phase of the Ti-Ag alloys decreased as the Ag concentration increased. TiAg present in the alloys dissolved preferentially, but Ti2Ag did not. The rest potentials of the Ti-Ag alloys were significantly higher than that of pure titanium. The elution test and the rest-potential measurement revealed that the Ti-Ag alloys, which formed a single α-titanium structure or contained a titanium and Ti2Ag, had excellent corrosion resistance that was comparable or superior to that of pure titanium.

The purpose of this study was to evaluate the corrosion resistance of experimental dental Ti-Ag alloys in 0.9% NaCl solution. Open-circuit potential (OCP) measurement and elution tests of the alloys with 5–30% Ag were performed. The amounts of both Ti and Ag ions released from the alloys with Ag � 20% were below the detection limit. A very small amount of Ti ions was released from some of the 22.5% Ag specimens and some of the 25% Ag specimens. The time for the Ti-Ag alloys with 5–25% Ag to become the stable potential was earlier than that for titanium, and the OCP of the alloys was higher than that of titanium. These results indicated that the corrosion resistance of the alloys with 5– 25% Ag was equivalent to that of titanium. On the other hand, it was suggested that the precipitation of TiAg deteriorated the corrosion resistance of Ti-Ag alloys because TiAg dissolved preferentially in the NaCl solution. Ti-Ag alloys with 5–25% Ag can be used not only as dental restorative materials but also as dental implant materials. [doi:10.2320/matertrans.M2009355]

Objectives: A nondestructive, rapid, and practical method of dental alloy sorting is desirable. In this study, the hypothesis to be tested is that dental alloys show significantly different and high thermoelectric power values, on the basis of which alloy sorting is possible.Methods: Six silver-colored commercial dental casting alloys are used in this study: two silver alloys, one gold-silver-palladium alloy, one cobalt-chromium alloy, one nickel-chromium alloy, and one titanium alloy. The thermoelectric power of their castings was determined against constantan using a simple apparatus developed in a previous study. Linear least square fitting was applied to the measured thermal-EMF-temperature curve to determine the thermoelectric power for the temperature ranges of 298.303 K (temperature difference Δt = 5 K), 298.308 K (Δt=10 K), 298.313 K (Δt=15 K), and 298.318 K (Δt=20 K). The results were analyzed using one-way ANOVA and by the Scheffefs test at a significance level of α=0.01.Results: When the temperature difference was 10 K or less, the difference in the thermoelectric powers of the alloys was not always statistically significant. However, when the temperature difference was 15 K or more, the thermoelectric powers of the six alloys differed significantly.Conclusions: The results indicated the feasibility of rapid sorting of specific dental alloys by the thermoelectric method, provided a sufficiently large temperature difference is achieved. (Eur J Dent 2010;4:66-70)

This study investigated the machinability of titanium, two commercial titanium alloys (Ti-6Al-4V and Ti-6Al-7Nb) and free-cutting brass using the cutting temperature. The cutting temperature was estimated by measuring the thermal electromotive force of the tool-workpiece thermocouple during cutting. The thermoelectric power of each metal relative to the tool had previously been determined. The metals were slotted using a milling machine and carbide square end mills under four cutting conditions. The cutting temperatures of Ti-6Al-4V and Ti-6Al-7Nb were significantly higher than that of the titanium, while that of the free-cutting brass was lower. This result coincided with the relationship of the magnitude of the cutting forces measured in a previous study. For each metal, the cutting temperature became higher when the depth of cut or the cutting speed and feed increased. The increase in the cutting speed and feed was more influential on the value than the increase in the depth of cut when two cutting conditions with the same removal rates were compared. The results demonstrated that cutting temperature measurement can be utilized to develop a new material for dental CAD/CAM applications and to optimize the cutting conditions.

The purpose of this study was to improve the grindability of titanium by alloying with zirconium. The grindability of dental cast Ti-Zr alloys (10, 20, 30, 40 and 50 mass% Zr) was evaluated using a carborundum wheel. The Ti-Zr alloys up to 30 mass% Zr formed an α structure, and the 40 mass% Zr and 50 mass% Zr alloys formed an α′ structure. The Ti-40 mass% Zr alloy at up to 1000 m/min and the Ti-50 mass% Zr alloy at up to 1250 m/min exhibited significantly higher grindability than titanium. More than twice the volume of metal was removed from the alloys than from titanium per minute. The improved grindability could be attributed to the α′ structure in addition to the decrease in elongation. The Ti-Zr alloys, which formed an α′ phase structure, are candidates for use as machinable biomaterial in dental applications.

Ti-Ag alloys with 20 and 25 mass% Ag were prepared; their surfaces were polished using silicon carbide abrasive papers. The polished alloys were immersed in a simulated body fluid (SBF), and their surfaces were observed by scanning electron microscope (SEM) to investigate the spontaneous formation of calcium phosphates. The precipitates formed on the alloys were qualitatively and quantitatively analyzed using an electron probe microanalyzer (EPMA), with pure titanium and silver used as controls. Hardness and surface roughness, which was measured as the height parameter Ra, were examined, and their effect on calcium phosphate formation was elucidated. On immersion in SBF, calcium phosphates were formed on the Ti-Ag alloys and pure titanium but not on pure silver. The amount of the precipitate and the concentration ratios of calcium to phosphorus in the precipitates of the Ti-Ag alloys and pure titanium did not differ significantly. The Ti-Ag alloys showed significantly higher hardness and lower Ra values than pure titanium. The Ra values of the metals decreased as their hardness increased. The Ra values of the metals appeared to have very little effect on calcium phosphate formation. The results of this study have verified the biocompatibility of the Ti-Ag alloys, making them suitable for use as dental and orthopedic implants.

This study is an investigation of the machinability of experimental Ti-Cu alloys (2, 5, and 10 mass% Cu) as new dental titanium alloy candidates for CAD/CAM use. The alloys were slotted with a vertical milling machine and carbide square end mills under two cutting conditions. Their machinability was evaluated through cutting force using a three-component force transducer fixed on the table of the milling machine. The horizontal cutting forces of the Ti-Cu alloys tended to increase as the concentration of copper increased. The feed force for Ti-10%Cu was more than twice as large as that for titanium under both cutting conditions. Alloying with copper reduced the machinability of titanium under the present cutting conditions. The adverse effect on the cutting force was attributed to the higher degree of tensile strength and hardness of the Ti-Cu alloys than of titanium.

This study investigated the machinability of experimental Ti-Ag alloys (5, 10, 20, and 30 mass% Ag) as a new dental titanium alloy candidate for CAD/CAM use. The alloys were slotted with a vertical milling machine and carbide square end mills under two cutting conditions. Machinability was evaluated through cutting force using a three-component force transducer fixed on the table of the milling machine. The horizontal cutting force of the Ti-Ag alloys tended to decrease as the concentration of silver increased. Values of the component of the horizontal cutting force perpendicular to the feed direction for Ti-20% Ag and Ti-30% Ag were more than 20% lower than those for titanium under both cutting conditions. Alloying with silver significantly improved the machinability of titanium in terms of cutting force under the present cutting conditions.

As part of our systematic studies characterizing the properties of titanium alloys, we investigated the grindability of a series of cast Ti-Hf alloys. Alloy buttons with hafnium concentrations up to 40 mass% were made using an argon-arc melting furnace. Each button was cast into a magnesia-based mold using a dental titanium casting machine; three specimens were made for each metal. Prior to testing, the hardened surface layer was removed. The specimens were ground at five different speeds for 1 min at 0.98 N using a carborundum wheel on an electric dental handpiece. Grindability was evaluated as the volume of metal removed per minute (grinding rate) and the volume ratio of metal removed compared to the wheel material lost (grinding ratio). The data were analyzed using ANOVA. A trend of increasing grindability was found with increasing amounts of hafnium, although there was no statistical difference in the grindability with increasing hafnium contents. We also found that hafnium may be used to harden or strengthen titanium without deteriorating the grindability.

Anodic polarization tests were performed in 0.9% NaCl and 1% lactic acid solutions to characterize the relationship between the corrosion behavior and the microstructures of cast Ti-Ag (5-40% Ag) alloys. The anodic polarization curves for the Ti-Ag alloys up to 17.5% Ag were similar to those for pure titanium in both solutions. On the other hand, an abrupt increase in the current density was observed for the alloys with more than 20% Ag in the NaCl solution and with more than 27.5% Ag in the lactic acid solution. The microstructures of the corroded alloy surfaces indicated the deterioration of precipitated intermetallic compounds along the grain boundaries. The Ti-Ag alloys up to 17.5% Ag had excellent corrosion resistance similar to that of pure titanium. The alloys with 20-25% Ag may be also used as dental alloys, since they passivated again immediately after preferential dissolution in the NaCl solution.

The aim of this investigation was to evaluate the metal-ceramic bonding of Au-1.6 wt% Ti alloy. Therefore, the coefficient of thermal expansion, modulus of elasticity, ceramic bonding strength, and hardness of Au-1.6 wt% Ti alloy were measured. The metal-ceramic interface was observed by EPMA to investigate its bonding mechanism. The Au-1.6 wt% Ti alloy showed a coefficient of thermal expansion close to that of conventional precious metal alloys for metal-ceramics. Bonding strength was 25 MPa or higher for all specimens--whether ceramic-fired directly after casting, or following oxidation treatment or age hardening. Specimens subjected to oxidation treatment showed slightly lower post-firing hardness than those age-hardened. EPMA observation showed an accumulation of Ti and O contents on the alloy side at the metal-ceramic interface.

In this study, the grindability of cast magnetic alloys (Fe-Pt-Nb magnetic alloy and magnetic stainless steel) was evaluated and compared with that of conventional dental casting alloys (Ag-Pd-Au alloy, Type 4 gold alloy, and cobalt-chromium alloy). Grindability was evaluated in terms of grinding rate (i.e., volume of metal removed per minute) and grinding ratio (i.e., volume ratio of metal removed compared to wheel material lost). Solution treated Fe-Pt-Nb magnetic alloy had a significantly higher grinding rate than the aged one at a grinding speed of 750-1500 m x min(-1). At 500 m x min(-1), there were no significant differences in grinding rate between solution treated and aged Fe-Pt-Nb magnetic alloys. At a lower speed of 500 m x min(-1) or 750 m x min(-1), it was found that the grinding rates of aged Fe-Pt-Nb magnetic alloy and stainless steel were higher than those of conventional casting alloys.

In the present study, the machinability of titanium, Ti-6Al-4V, Ti-6A1-7Nb, and free-cutting brass was evaluated using a milling machine. The metals were slotted with square end mills under four cutting conditions. The cutting force and the rotational speed of the spindle were measured. The cutting forces for Ti-6Al-4V and Ti-6Al-7Nb were higher and that for brass was lower than that for titanium. The rotational speed of the spindle was barely affected by cutting. The cross sections of the Ti-6Al-4V and Ti-6Al-7Nb chips were more clearly serrated than those of titanium, which is an indication of difficult-to-cut metals. There was no marked difference in the surface roughness of the cut surfaces among the metals. Cutting force and the appearance of the metal chips were found to be useful as indices of machinability and will aid in the development of new alloys for dental CAD/CAM and the selection of suitable machining conditions.

Anodic polarization was performed in 0.9% NaCl and 1% lactic acid solutions to characterize the relationship between the corrosion behavior and microstructures of cast Ti-Au (5-40%) alloys. An abrupt increase in the current density occurred at approximately 0.6 V vs. SCE for the 30% and 40% Au alloys in the 0.9% NaCl solution. The microstructures after corrosion testing indicated that this breakdown may have been caused by the preferential dissolution of the Ti3Au. However, the potential for preferential dissolution was higher than the breakdown potential of stainless steel or Co-Cr alloy, which meant that the corrosion resistance of the Ti-Au alloys was superior. In 1% lactic acid solution, the corrosion resistance of the Ti-Au alloys was excellent, with no breakdown at any composition. In the present test solutions, the Ti-Au alloys up to 20% Au had good corrosion resistance comparable to that for pure titanium.

Experimental Ti-Au alloys (5, 10, 20 and 40 mass% Au) were made. Mechanical properties and grindability of the castings of the Ti-Au alloys were examined. As the concentration of gold increased to 20%, the yield strength and the tensile strength of the Ti-Au alloys became higher without markedly deteriorating their ductility. This higher strength can be explained by the solid-solution strengthening of the a titanium. The Ti-40%Au alloy became brittle because the intermetallic compound Ti3Au precipitated intensively near the grain boundaries. There was no significant difference in the grinding rate and grinding ratio among all the Ti-Au alloys and the pure titanium at any speed.

To establish a method of determining the machinability of dental materials for CAD/CAM systems, the machinability of titanium, two titanium alloys (Ti-6Al-4V and Ti-6Al-7Nb), and free-cutting brass was evaluated through cutting force and spindle motor current. The metals were slotted using a milling machine and square end mills at four cutting conditions. Both the static and dynamic components of the cutting force represented well the machinability of the metals tested: the machinability of Ti-6Al-4V and Ti-6Al-7Nb was worse than that of titanium, while that of free-cutting brass was better. On the other hand, the results indicated that the spindle motor current was not sensitive enough to detect the material difference among the titanium and its alloys.

Objectives. The purpose of the present study was to evaluate the grindability of a series of cast Ti–Cu alloys in order to develop a titanium alloy with better grindability than commercially pure titanium (CP Ti), which is considered to be one of the most difficult metals to machine. Methods. Experimental Ti–Cu alloys (0.5, 1.0, 2.0, 5.0, and 10.0 mass% Cu) were made in an argon-arc melting furnace. Each alloy was cast into a magnesia mold using a centrifugal casting machine. Cast alloy slabs (3.5 mm×8.5 mm×30.5 mm), from which the hardened surface layer (250 μm) was removed, were ground using a SiC abrasive wheel on an electric handpiece at four circumferential speeds (500, 750, 1000, or 1250 m/min) at 0.98 N (100 gf). Grindability was evaluated by measuring the amount of metal volume removed after grinding for 1 min. Data were compared to those for CP Ti and Ti–6Al–4V. Results. For all speeds, Ti–10% Cu alloy exhibited the highest grindability. For the Ti–Cu alloys with a Cu content of 2% or less, the highest grindability corresponded to an intermediate speed. It was observed that the grindability increased with an increase in the Cu concentration compared to CP Ti, particularly for the 5 or 10% Cu alloys at a circumferential speed of 1000 m/min or above. Significance. By alloying with copper, the cast titanium exhibited better grindability at high speed. The continuous precipitation of Ti2Cu among the α-matrix grains made this material less ductile and facilitated more effective grinding because small broken segments more readily formed.

Experimental Ti-Ag alloys (5, 10, and 20 mass% Ag) and Ti-Cu alloys (2, 5, and 10 mass% Cu) were cast into magnesia molds using a dental casting machine, and their grindability was investigated. At the lowest grinding speed (500 m min(-1)), there were no statistical differences among the grindability values of the titanium and titanium alloys. The grindability of the alloys increased as the grinding speed increased. At the highest grinding speed (1500 m x min(-1)), the grindability of the 20% Ag, 5% Cu, and 10% Cu alloys was significantly higher than that of titanium. It was found that alloying with silver or copper improved the grindability of titanium, particularly at a high speed. It appeared that the decrease in elongation caused by the precipitation of small amounts of intermetallic compounds primarily contributed to the favorable grindability of the experimental alloys.

In this study, experimental Ti-Ag alloys (5, 10, and 20 mass% Ag) and Ti-Cu alloys (2, 5, and 10 mass% Cu) were made in an argon-arc melting furnace. The alloys were cast into magnesia molds using an argon gas-pressure dental casting machine, and the mechanical properties and microstructures of the castings were investigated. As the concentration of silver or copper in the alloys increased, the tensile strength, yield strength, and hardness of the alloys became higher than those of CP Ti, and the elongation of the alloys became lower than that of CP Ti. Changes in the mechanical properties by alloying were considered to be caused by solid-solution strengthening of the a-phases and by precipitation of intermetallic compounds.

To optimize the properties of titanium for use in dentistry, alloying is necessary. This study reports on the characterization of some titanium alloys for grindability, wear, and corrosion resistance. Improvements in grindability and wear seemed to occur with the presence of the eutectoid in the alloy.

The effects of the β-stabilizing elements (Ag, Au, Co, Cr, Cu, Fe, Mn, and Pd) on the characteristics of the experimental binary titanium alloys were examined with respect to mechanical properties, high temperature reactivity, corrosion resistance, grindability and machinability. The addition of β stabilizers to titanium lowers the fusion temperature, improves working mechanical properties, and suppresses reactivity at high temperature while maintaining corrosion resistance. The Ti–Cr or Ti–Mn alloys display similar favorable properties as dental casting titanium alloys. On the other hand, the Ti–Ag alloys may belong to the free-cutting materials, and demonstrate inhibitory properties on biofilm formation without affecting normal microbial flora. The Ti-20mass%Ag alloy is especially noted for its potential use as a dental CAD/CAM alloy, which may be potentially used not only for dental use but also for other medical applications.

We developed experimental Ti–Ag alloys and characterized their ­properties. The mechanical properties and machinability of the Ti–Ag alloys were superior to those of pure titanium. The Ti–Ag alloy surfaces inhibited biofilm formation by Streptococcus mutans. The spontaneous formation of calcium phosphates on the Ti–Ag alloys upon immersion in simulated body fluid was confirmed. The corrosion resistance of the Ti–Ag alloys in a 0.9% NaCl solution and a 1% lactic acid solution was comparable to that of pure titanium. Further, we performed a tarnish resistance test, and found that the Ti–Ag alloys had excellent tarnish resistance in 0.1% Na2S solution, comparable or superior to that of pure titanium.

Titanium and titanium alloys are difficult to machine. This problem arises when milling, using dental CAD/CAM systems. In a previous study, an experimental binary titanium alloy with 20 mass% Ag showed good grindability. In this study, the fracture strength of porcelain fused to a Ti-20 mass% Ag alloy crown made using a CAD/CAM (GN-1, GC, Japan) system is investigated. As controls, similar pure titanium (JIS grade II) samples made using cast and using the CAD/CAM system were also examined. The crowns were made assuming a maxillary left central tooth. The fracture strengths were statistically analyzed using one-way ANOVA followed by Tukey pairwise tests. There was no significant difference in the fracture strength of porcelain fused to metal crowns between the Ti-20 mass% Ag alloy frame crowns and the pure titanium frame crowns.

This study examined the mechanical properties of a series of Ti-Hf alloys. Titanium alloys with 10 to 40 mass % Hf were made with titanium and hafnium sponge in an argon-arc melting furnace. Specimens cast into magnesia-based investment molds were tested for yield strength, tensile strength, percentage elongation, and modulus of elasticity. Vickers microhardness was determined at 25 to 600 microm from the cast surface. X-ray diffractometry was also performed. Commercially pure Ti (CP Ti) and pure Ti prepared from titanium sponge were used as controls. The data (n = 5) were analyzed with a one-way ANOVA and the Student-Newman-Keuls test (alpha = 0.05). The diffraction peaks of all the metals matched those for alpha Ti; no beta phase peaks were found. Alloys with Hfor = 25% had significantly (p0.05) higher yield and tensile strength compared to the CP Ti and pure Ti. There were no significant differences (p0.05) in elongation among all the Ti-Hf alloys and CP Ti, whereas the elongation of alloys with Hfor = 30% was significantly (p0.05) lower than that of the pure Ti. The cast Ti-Hf alloys tested can be considered viable alternatives to CP Ti because they were stronger than CP Ti and had similar elongation.

Summary Objectives This study investigated the effect of alloying titanium with gold, silver, or copper on the elastic properties of the alloys. Methods A series of binary titanium alloys was made with four concentrations of gold, silver, or copper (5, 10, 20, and 30 mass%) in an argon-arc melting furnace. The Young's moduli and Poisson's ratios of the alloy castings were determined with an ultrasonic-pulse method. The density of each alloy was previously measured by the Archimedes' principle. Results were analyzed using one-way ANOVA and the Scheffe's test. Results The densities of Ti–Au, Ti–Ag, and Ti–Cu alloys monotonically increased as the concentration of alloying elements increased. As the concentration of gold or silver increased to 20%, the Young's modulus significantly decreased, followed by a subsequent increase in value. As the concentration of copper increased, the Young's modulus monotonically increased. The Young's moduli of all the Ti–Cu alloys were significantly higher than that of the titanium. Significance The density of all the experimental alloys was virtually independent of the alloy phases, while the Young's moduli and Poisson's ratios of the alloys were dependent. The addition of gold or silver slightly reduced the Young's modulus of the titanium when the alloy phase was single α. The increase in the Young's modulus of the Ti–Cu alloys is probably due to the precipitation of intermetallic compound Ti2Cu. Copper turned out to be a moderate stiffener that gains a Young's modulus of titanium up to 20% at the copper concentration of 30 mass%.

Aiming at developing a dental titanium alloy with better mechanical properties and machinability than unalloyed titanium, a series of Ti-Nb alloys with Nb concentrations up to 30% was made. They were cast into magnesia-based molds using a dental casting machine and the mechanical properties and grindability of the castings were examined. The hardness of the alloys with Nb concentrations of 5% and above was significantly higher than that of titanium. The yield strength and tensile strength of the alloys with Nb concentrations of 10% and above were significantly higher than those of titanium, while the elongation was significantly lower. A small addition of niobium to titanium did not contribute to improving the grindability of titanium. The Ti-30% Nb alloy exhibited significantly better grindability at low grinding speed with higher hardness, strength, and Young's modulus than titanium, presumably due to precipitation of the omega phase in the beta matrix.

This study evaluated the mechanical properties of cast Ti-Cu alloys with the hope of developing an alloy for dental casting with better mechanical properties than unalloyed titanium.Ti-Cu alloys with five concentrations of copper (0.5, 1.0, 2.0, 5.0 and 10.0 mass%) were made in an argon-arc melting furnace. The alloys were cast into magnesia-based molds using a centrifugal casting machine. The microstructure, microhardness profile of the specimen cross section, tensile strength, yield strength, and elongation were determined for the castings. Scanning electron microscope fractography was undertaken for the fractured surfaces after tensile testing. XRD was performed on the polished specimens. Results were analyzed using one-way ANOVA and the Student-Newman-Keuls tests.The mean tensile strengths of all the cast Ti-Cu alloys were significantly (p0.05) higher than for cast commercially pure titanium (CP Ti). Of the Ti-Cu alloys tested, the 5 and 10% Cu alloys had significantly higher strength than the rest. The 10% Cu alloy exhibited the lowest mean elongation. CP Ti and the 0.5 and 1% Cu alloys showed higher ductility. The bulk hardness of all the cast Ti-Cu alloys, except for the 10% Cu alloy, and CP Ti was approximately the same.By alloying with copper, the cast titanium became stronger. Increases in the tensile strength (30%) and yield strength (40%) over CP Ti were obtained for the 5% Cu alloy. Elongation was approximately 3%, which was similar to cast Ti-6Al-4V. Ti-Cu alloys, such as the 5% Cu alloy, could be used for prosthetic dental applications if other properties necessary for dental castings are obtained.

Experimental Ti–Au (5–20 mass% Au), Ti–Ag (5–20 mass% Ag) and Ti–Cu (2–10 mass% Cu) alloys were made. Mechanical properties and grindability of the alloys were examined. The hardness and tensile strength became higher and the elongation became lower than pure titanium. The grindability of titanium was improved by alloying with silver or copper, especially at high speed grinding.

This study examined the mechanical properties of a series of Ti–Hf alloys. Titanium alloys with 10–40 wt.% Hf were made with titanium and hafnium sponge in an argon-arc melting furnace. The cast Ti–Hf alloys tested can be considered viable alternatives to CP Ti since they were stronger than CP Ti and had similar elongation.

To examine a new concept for computerized production of dental prostheses, an experimental porcelain forming system was devised. Unlike other dental CAM systems, the system is intended to form porcelain much as human technicians do. The system builds up an object by alternately applying water and droplets of porcelain powder. Test specimens were made by forming porcelain powder into square plates under different forming conditions. Surface characteristics and shapes of formed porcelain were found to be affected by conditions such as quantity of water, forming area and forming thickness. The proper quantity of water for forming was influenced by evaporation. It was concluded that investigation into feedback control of the water supply in response to varying forming conditions is required.