Titanium often ranks as the engineer's first choice as a structural material for jet aircraft, racecars, oil-drilling equipment or prosthetic body implants. And it's little wonder: titanium alloys are light and strong, as well as heat- and corrosion-resistant. The silvery-gray metal is pricey, however, compared with stainless steel and aluminum, a fact that limits its use. Scarcity is not the issue--titanium is the ninth most common element on earth--but the high cost of wresting the pure metal from the ore translates into expensive products.

This past March the U.S. Defense Advanced Research Projects Agency (DARPA) tapped three materials research groups to address this persistent problem. Agency managers awarded separate contracts totaling $5 million to Titanium Metals Corporation (TIMET) and two others to fund parallel efforts to develop potentially low-cost production routes for titanium and its alloys.

Chemists have two ways to pry metal from an oxide ore. One, electrolysis, decomposes the ore into its elementary constituents with electricity. Aluminum manufacturing employs this method. The alternative, called chemical reduction, involves reacting the ore with a substance that has a greater affinity for oxygen than the metal to be extracted. This procedure is used to refine iron.

In current industry practice, titanium ore undergoes chemical reduction. But unlike iron ore, from which the oxygen is removed cheaply by reaction with carbon coke, extracting titanium requires a laborious, two-stage procedure. Plant technicians heat the ore in the presence of carbon and chlorine to create titanium tetrachloride, from which titanium is extracted by reacting the tetrachloride with magnesium. The result is titanium sponge, a porous form of the metal with salt compounds entrapped in the spaces. This process, invented by William J. Kroll in the late 1930s, has remained the chief titanium-refining route since industrial production began after World War II.

The Kroll process has drawbacks, however. The reducing agents for titanium are more expensive than coke. Kroll production is a batch process that requires the reaction vessels to be repeatedly emptied, refilled and sealed, rather than a continuous operation. And titanium tetrachloride is a volatile, corrosive liquid that requires special handling. In fact, soon after the Kroll process was introduced in the 1950s, its inventor reportedly predicted that an electrolytic process would replace it within 15 years. This shift never occurred, despite many attempts and millions in investment.

Thanks to a bit of serendipity, the most prominent of the electrolytic extraction techniques could eventually lead to cheaper titanium. In 1993 University of Cambridge metallurgists Derek J. Fray, Tom W. Farthing and George Zheng Chen were experimenting with electrolysis in an attempt to eliminate the oxide film that forms when titanium is exposed to air. The trio hoped that electrical flow through the titanium would pull the oxygen ions to the surface, where they could be removed. Instead the team observed an unexpected side effect: the process converted titanium oxides directly into the pure metal--an astonishing result.

In standard electrolysis, chemists dissolve the compound that is to be broken down in a conducting fluid called an electrolyte, which conveys charged ions from one electrode to another. For the electrolysis of titanium dioxide, metallurgists prefer an electrolyte of molten calcium chloride. Previous unsuccessful experiments along these lines relied on dissolving the tetrachloride (or the dioxide form) into the molten salts.

The Cambridge group's calculations showed, however, that it should be possible to reduce titanium dioxide electrolytically without having to dissolve it. The team used a cathode made of titanium dioxide. Other materials scientists had neglected to test this cell design because they believed that solid titanium dioxide--an insulator--could not be electrolyzed, Fray says. But the team's observations suggested that this electrolysis could in fact occur because titanium dioxide conducts electricity once some oxygen is taken out of the compound. When they tried it out, it worked. "It was shocking to see the little pellet of white titanium dioxide, which looks like an aspirin pill, being transformed into a piece of titanium," Fray recalls. "We sat around asking, 'Why hasn't this been done before?'"

That the electrolysis converted oxide straight to metal would have gratified even a medieval alchemist. And if the process could be scaled up to industrial levels, the kind of riches for which alchemists always strove might be attainable. In addition to producing titanium more cheaply, the method might also work for other premium-priced metals, such as chromium and zirconium. Further, by forming the cathode from mixed metal oxide precursors, it might be possible to create titanium alloys in a single run, rather than via the conventional method of melting together alloy ingredients.

The FFC Cambridge process converted titanium oxides directly into the pure metal--an astonishing result.

The U.K. defense ministry soon took notice of the Fray/Farthing/Chen process, which by then had come to be known as the FFC Cambridge method (after the inventors' initials and their employer). The U.K.'s military research agency licensed the technology and supported the team's investigations until 1998, when a company--British Titanium--was established to sublicense and commercialize the technology. This step led to a pilot plant that produces kilogram-size quantities of titanium.

The high costs of fully developing the commercial process hindered further progress for several years, however, despite considerable attention from industry. After gauging DARPA's interest in providing funds for the development of cheaper refining routes, TIMET sub-sublicensed the technology and proposed leading a U.S. government-funded R&D project. By March, DARPA had opted to invest in the FFC Cambridge approach.

The TIMET research syndicate will include scientists from defense contractors General Electric Aircraft Engines, United Defense Ltd. Partners, and Pratt & Whitney, as well as experts from Cambridge and the University of California at Berkeley. "By the third quarter of 2004, we're to have demonstrated a process capable of producing 50 pounds of metal a day," says Stephen Fox, U.S. director of research at TIMET. Success in that effort could lead to further DARPA money to subsidize a scale-up to 500 pounds a day and eventually to commercial levels measured in tons a day.

Fox points to the possibility of great payoffs if FFC Cambridge-based manufacture of titanium and its alloys can be achieved. "The process offers control over the resulting product form--powdered metal or pieces of sponge in a tailored size range," he says. "These could feed right into existing part-manufacturing processes, or, potentially, traditional remelting and fabrication steps might be avoided by directly consolidating the metal into a near-finished form."

Many hurdles still exist. Fox lists as key the detailed engineering of the cell for operations on a mass scale, the development of process controls, and the manner by which the reactive precursors and final materials are transported in and out of the cell. "Much remains to be done to get costs down," he notes.

Not everyone is optimistic. "I take a skeptical view of these efforts because these new process technologies are extremely high risk and very costly to develop," comments Firoze E. Katrak, metallurgist and metals market analyst at Charles River Associates. Near-term price reductions of titanium sponge, he believes, may come more readily from converting the Kroll process from a batch process into a semicontinuous one. So the debate about the best way to achieve low-cost titanium persists. But the big payoffs--such as making a next-generation airliner or a less weighty SUV--ensure that the quest will continue.