Martin Marietta Corp., in its latest action to reduce the huge debt it incurred defending itself against Bendix Corp.'s takeover overtures, announced plans yesterday to sell part of its chemical division to a Swiss company for an undisclosed amount.

The Bethesda-based aerospace firm said it had agreed in principle to sell its Sodyeco division, which makes dyes and organic chemicals, to Sandoz Ltd., a maker of drugs and chemicals. The two companies hope to announce a definitive agreement on the transaction later this month.

Sodyeco is based in Charlotte, N.C., and has 600 employes there. It also has facilities in Brazil and Mexico. A Martin Marietta spokesman would not give any financial breakdown of the division's size, but said it was a relatively small part of the company's chemical operations, themselves small in relation to the rest of the company.

The proposed sale of Sodyeco is the latest in a series of asset sales, plant closings and other actions taken by Martin Marietta in recent weeks in an effort to reduce the $900 million debt the company ran up buying control of Bendix last summer to thwart that company's attempts to take over Marietta. Marietta later struck a bargain with Allied Corp. that left Allied with ownership of Bendix and a 37 percent stake in Marietta.