A top Xerox Corp. official will be named today to succeed the late Robert Noyce as chief executive of Sematech, the industry-government consortium designed to regain the nation's lead in computer-chip technology, industry sources said.

William J. Spencer, Xerox's senior technical officer, will take over the Austin, Tex., consortium at a time when the unusual venture is being carefully watched as a test case of how the Asian model of government-industry cooperation can fare in the United States.

The choice of Spencer comes after a nationwide search for someone who could combine technical knowledge of the industry with an ability to sell ideas in Washington. Spencer, 60, a PhD physicist, worked at Bell Laboratories and Sandia National Laboratory before joining Xerox a decade ago. At Xerox he built the firm's semiconductor research lab before rising to be head of the company's research center in Palo Alto, Calif., and then to corporate headquarters in Connecticut.

Spencer's appointment comes at a crucial moment for Sematech. With its initial five-year charter for federal funding expiring in 1992, the cooperative generally has been praised for its progress to date but has yet to prove that it will help in a major way to resuscitate the struggling U.S. chip industry. At the same time, it is serving as a role model for Capitol Hill lawmakers who are weighing legislation that would permit the Pentagon and Commerce Department to fund similar, though smaller-scale, industry-government ventures.

Funded with $100 million a year from the Pentagon, and roughly the same amount from its 14 industrial members, Sematech has laid out an ambitious plan to advance the manufacturing know-how of U.S. makers of semiconductors, the tiny chips that are sometimes called the crude oil of the world's $600 billion electronics industry.

U.S. makers continue to lose ground to Japanese firms, which hold just over half of the $55 billion worldwide semiconductor market. Under the leadership of Noyce, who died in June, Sematech won widespread support on Capitol Hill, where helping to save the chip industry has become a popular rallying cry.

Even in the White House, which officially opposes any sort of "industrial policy" to aid specific industries, at least some people appear sympathetic to the chip industry.

Much of Sematech's effort has gone toward propping up the makers of sophisticated equipment used to manufacture semiconductors. Sematech has helped to define and fund new technologies and in one case even purchased equipment from a struggling U.S. supplier and provided it to chipmakers for evaluation.

According to some Sematech members, the efforts are starting to pay off. A spokesman for Micron Technology Inc. of Idaho, for example, said his firm was able to acquire new equipment more quickly because it had already been screened by Sematech.

The consortium's primary technical goals still remain in the future:It hopes to reach its key technical milestone in reducing the dimensions of chips by 1993.

In the meantime, the consortium has been working to change industry culture. A General Accounting Office report found recently that equipment companies complained that chipmakers remain too short-term oriented in their purchase decisions -- a problem Sematech said it is trying to correct with a new program designed to encourage long-term partnerships.

Already, chip companies -- each of whom send staff members to work at Sematech -- are sharing more technological know-how with each other than in the past. "Before Sematech, everybody thought he had the keys to the kingdom," said Wilfred Corrigan, chairman of LSI Logic Corp., a California chipmaker.

Although Noyce set all this in motion, his successor will have to show the results. "Noyce gave them a direction. ... {Now the} short-term objective is implementation. Another concern is what's Sematech's role in {future} years," said Jeffrey Mayer, a Commerce Department official who wrote a report on Sematech released yesterday.

One acquaintance said Spencer is up to the task. "Bill is a wonderful manager, a superb scientific and technical politician and a great windsurfer," said John Shoch, a venture capitalist who worked with Spencer at Xerox.

According to Shoch, Spencer helped Xerox move some of its innovative technologies into the marketplace. Under his tenure, Xerox spun off new firms to commercialize technologies in lasers, computer networking and software, Shoch said.