A top executive of Bendix Corp. said today he expects the company's board to reject United Technologies Corp.'s bid to buy Bendix and vowed the board will "come out swinging" in its tangled takeover battle with Martin Marietta Corp.

The Bendix board is scheduled to meet in New York Friday to discuss United Technologies' $75-a-share bid for Bendix.

The company official, Fred W. Searby, president of Bendix's industrial group and a director of the company, left little doubt that the offer will be turned down, but gave no clue to Bendix's next move.

Searby, whose background includes expertise in corporate acquisitions, was interviewed at the International Machine Tool Show here, where Bendix is exhibiting its machine tools and sophisticated robotics equipment.

Bendix is offering $48 a share for Martin Marietta, which has retaliated with its own $75-a-share offer for Bendix. Earlier this week, United Technologies made it a three-way fight by mounting its own $75-a-share offer for Bendix. UTC said if the bid were successful, it would split up Bendix and sell part to Martin Marietta.

Searby said UTC's bid will likely be rejected because "it's the same offer that Martin Marietta made, but less." Both Martin and UTC are offering $75 a share for about half of Bendix stock; each plans to acquire the rest of the Bendix shares through an exchange of shares.

Searby would not say what steps Bendix might take to head off the United Technologies' threat. But a source close to the Bendix board said, "We'll probably do something interesting. . . . I don't think Bendix Chairman Bill Agee is the kind of guy who is short on ideas."

Searby, echoing the Bendix rejection of Martin Marietta's offer, said the $75-a-share bid is "grossly inadequate and also unfair."

Asked what he thought would be a fair per-share price for Bendix, Searby replied, "I wouldn't sell it for less than $90." Bendix stock closed at $61 per share in trading on the New York Stock exchange today, off 1 1/2 after a six-point surge on Wednesday in response to the Unted Technologies offer.

Bendix originally offered $43-a-share for Martin Marietta two weeks ago, and earlier this week announced that it had received tenders, or pledges, for 58 percent of the Bethesda aerospace company's stock. Bendix then raised its offer to $48 a share.

Searby said Bendix increased the bid to lock in the already tendered shares, which can be withdrawn any time before Sept. 16. "You're trying to keep those in that have already tendered," he said.

Although some analysts have predicted Bendix will raise its offer further, Searby said $48 a share was enough.

"My point of view is that $43 is a fair price; $48 is a super fair price," he said. Hinting that Bendix might not raise the ante again, he said, "We're not going to throw money at something simply to acquire it, if it isn't a good investment."

Bendix, which had made no secret that it was looking for a high technology company to acquire, believes that Martin Marietta would be a good acquisition, Searby said. "There is good synergy," he said. "The Martin Marietta-Bendix combination is something that makes a lot of sense."

One question that will probably be considered at tomorrow's board meeting, Searby said, is whether participants in Bendix's employe stock ownership plan can tender their shares to Martin Marietta or United Technologies. Most of the participants are current Bendix employes.

At present, Searby said, there is no mechanism available to permit invididual employes to offer to sell their stock. The plan owns about 23 percent of Bendix's outstanding common stock and could be a major factor in the battle. "They may want the $75," he said of the employes, "but they may be doing so in a way that changes the character of the company and costs them their job."

Martin Marietta's tender offer for Bendix stock expired at midnight tonight, and officials said it will be several days before it is known how many shares were offered to Marietta.

Martin Marietta said it plans to sue Citibank, the trustee of the Bendix employes stock plan, in an effort to free up the large block of Bendix shares. Marietta officials claim the bank has failed to meet its legal responsibility to the workers by not giving them the chance to take advantage of Martin's offer.

Bendix officials say the rules of the plan permit shareholders to withdraw their shares only at the end of a month -- too late to offer them to Martin Marietta.

Martin Marietta's chairman, Thomas G. Pownall, opened another front in his company's battle against Bendix by telling key members of Congress that the Bendix takeover attempt could be detrimental to national security.

Referring to Martin Marietta's work on such weapons systems as the Pershing and MX missiles, Pownall asked, "what happens to this work in the hands of a management with no credentials in prime systems?" He quoted a Business Week article saying Bendix chairman Agee "sees himself as a wily financier," not an expert on defense operations