Directors at General Motors Corp. have approved the sale of its Hughes Electronics aerospace and defense systems arm to Raytheon Co. Officials expect the $9.5 billion merger to close in the next six months, pending regulatory and shareholder approval. Peter R. D'Angelo, Raytheon's executive vice president and CFO, told Photonics Spectra that Hughes' defense electronics expertise will make a strong combination with current competencies, particularly with its Raytheon Amber subsidiary. He said the company can now compete "among the top players" in the missile and intelligent systems industries.