No, the raid has its own chat channel that all in the raid can see. The default use for this channel is /ra.

You can still chat in party, but it will only go to your current party members.

Pressing the letter “R” will automatically open a private message (Whisper) chat window to the last player who sent you a private message. You can also type "/r" and then your message. Whisper text appears in purple text by default.

To send a private message to another player, type in /w (character name) (message). The chat field will change to display the name of the character and you will be able to type in your message. Alternately you can use /tell or /t in place of /w. Also, if you wish to reply back to the last player who sent you a private message, simply press "R" and type your response to reply back to that player.